Method and device for beam recovery in mobile communication system in MTRP environment

Abstract

The present invention relates to a method of a first TRP, which may comprise the steps of: when a beam failure recovery request is received from a communication terminal, identifying whether the first TRP is connected to a second TRP communicating with the terminal through a backhaul; transmitting, to the terminal, a first message including a beam index of a candidate beam between the first TRP and the terminal, if the first TRP is not connected to the second TRP through the backhaul; receiving a first report message including beam index related information from the terminal in response to the first message; and determining a beam index to be used for communicating with the terminal based on the beam index related information.

Description

Technical Field

[0001] The present invention relates to a communication technology, and more particularly, the present invention relates to a technology for beam failure recovery in a multiple transmission and reception point (MTRP) environment. Background Art

[0002] Communication networks (e.g., 5G communication networks or 6G communication networks) are being developed to provide enhanced communication services compared to existing communication networks (e.g., long term evolution (LTE), LTE-Advanced, etc.). 5G communication networks (e.g., New Radio (NR) communication networks) can support frequency bands below 6 GHz and frequency bands above 6 GHz. In other words, 5G communication networks can support frequency region 1 (FR1) bands and / or FR2 bands. Compared with LTE communication networks, 5G communication networks can support various communication services and scenarios. For example, usage scenarios of 5G communication networks may include enhanced Mobile BroadBand (eMBB), UltraReliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), etc.

[0003] Compared with 5G communication networks, 6G communication networks can support a wide variety of communication services and scenarios. 6G communication networks can meet the requirements of ultra-performance, ultra-bandwidth, ultra-space, ultra-precision, ultra-intelligence and / or ultra-reliability. 6G communication networks can support multiple broadband bands and can be applied to various usage scenarios, such as terrestrial communication, non-terrestrial communication, sidelink communication, etc.

[0004] On the other hand, in 5G NR, multiple transmission and reception point (MTRP) technology refers to the technology that gNB uses physically separated multiple TRPs to communicate with terminals. MTRP technology helps to solve the problem of reduced quality of service (QoS) of cell-edge terminals far away from the base station, and alleviates inter-cell interference from base stations in different cells. In addition, it helps to provide alternative communication paths in environments with limited non-line-of-sight (NLOS) paths (for example, in the millimeter wave band).

[0005] In the current 3GPP standard, MTRP technology is classified into a coherent joint transmission (CJT) scheme and a non-coherent joint transmission (NCJT) scheme. In the CJT scheme, TRPs collaborate in a synchronous manner based on a reliable backhaul link between base stations connected to the TRPs. On the other hand, in the NCJT scheme, scheduling, pre-coding matrix selection, modulation, and coding schemes are determined uncoordinatedly between multiple TRPs supporting a single terminal.

[0006] Therefore, in the MTRP environment, when a beam failure occurs in the communication link between the TRP and the terminal, it may be necessary to define a beam failure recovery process that also takes into account the link between the terminal and other TRPs and the parameters required for the process. Summary of the invention

[0007] Technical issues

[0008] The present invention is directed to providing a method and apparatus for beam failure recovery in a mobile communication system having an MTRP environment.

[0009] Technical Solution

[0010] According to an exemplary embodiment of the present invention, a method of a terminal may include: in response to a beam failure occurring at a first transmit and receive point (TRP) communicating with the terminal, sending a beam failure recovery request to the first TRP; sending a first message to a second TRP communicating with the terminal, the first message including an identifier (ID) of the first TRP and a beam failure detection (BFD) indicator; receiving a second message from the first TRP, the second message including a corresponding beam index corresponding to a candidate beam to be used between the first TRP and the terminal; for the corresponding beam index, measuring a signal to interference plus noise ratio (SINR) of a first link communicating with the second TRP; in response to the first message, receiving a third message from the second TRP, the third message including an SINR threshold of the first link; and in response to the second message, sending a first report message to the first TRP, the first report message including information related to an index of a beam that meets the SINR threshold of the first link.

[0011] The method may further include: in response to the existence of a third TRP communicating with the terminal, sending a fourth message to the third TRP, the fourth message including the ID and BFD indicator of the first TRP; for the corresponding beam index, measuring the SINR of the second link communicating with the third TRP; and in response to the fourth message, receiving a fifth message from the third TRP, the fifth message including the SINR threshold of the second link, wherein the first report message further includes information related to the index of the beam that meets the SINR threshold of the second link.

[0012] The first report message may include: the ID of the second TRP, the index of the beam that meets the SINR threshold of the first link, the ID of the third TRP, and the index of the beam that meets the SINR threshold of the second link.

[0013] The first report message may include a common index among the indexes of the beams satisfying the SINR threshold of the first link and the indexes of the beams satisfying the SINR threshold of the second link.

[0014] Each of the second message and the first report message may be transmitted and received using a Radio Resource Control (RRC) signaling message.

[0015] When the first TRP and the second TRP are connected to the same base station, the first message may be sent using one of uplink control information (UCI), measurement report, or user equipment (UE) assistance information.

[0016] When the first TRP and the second TRP are connected to different base stations, the first message may be sent using a message based on a random access channel (RACH) access procedure.

[0017] A method of a first transmitting and receiving point (TRP) according to an exemplary embodiment of the present invention may include: when a beam failure recovery request is received from a terminal communicating with a first TRP, checking whether the first TRP is connected to a second TRP communicating with the terminal via a backhaul; in response to the first TRP not being connected to the second TRP via the backhaul, sending a first message to the terminal, the first message including a beam index of a candidate beam between the first TRP and the terminal; in response to the first message, receiving a first report message from the terminal, the first report message including information related to the index of the beam; and determining the index of the beam to be used for communicating with the terminal based on the information related to the index of the beam.

[0018] The first report message may include an identifier (ID) of the second TRP and an index of at least one beam that meets a signal to interference plus noise ratio (SINR) threshold of a first link between the second TRP and the terminal.

[0019] When there is a third TRP communicating with the terminal, the first report message may further include an ID of the third TRP ID and an index of at least one beam that meets the SINR threshold of the second link between the third TRP and the terminal.

[0020] When the first report message includes two or more beam indices, the index of the beam to be used for communication with the terminal may be determined based on the SINR reported together with the corresponding two or more beam indices.

[0021] Each of the first message and the first report message may be transmitted and received using a radio resource control (RRC) signaling message.

[0022] A method for a terminal according to an exemplary embodiment of the present invention may include: in response to a beam failure occurring at a first transmit and receive point (TRP) communicating with the terminal, sending a beam failure recovery request to the first TRP; sending a first message to a second TRP communicating with the terminal, the first message including an identifier (ID) of the first TRP and a beam failure detection (BFD) indicator; receiving a second message from the first TRP, the second message including a corresponding beam index corresponding to a candidate beam to be used between the first TRP and the terminal; measuring a signal to interference plus noise ratio (SINR) of a first link communicating with the second TRP for the corresponding beam index; sending a third message to the second TRP, the third message including the measured SINR for the corresponding beam index; receiving a fourth message from the second TRP in response to the first message, the fourth message including an index of at least one beam; and sending a first report message to the first TRP, the first report message including information related to the index of the beam based on the fourth message received from the second TRP.

[0023] The method may further include: in response to the existence of a third TRP communicating with the terminal, sending a fifth message to the third TRP, the fifth message including the ID and BFD indicator of the first TRP; for the corresponding beam index, measuring the SINR of the second link communicating with the third TRP; sending a sixth message to the third TRP, the sixth message including the measured SINR for the corresponding beam index; and in response to the fifth message, receiving a seventh message from the third TRP, the seventh message including the index of at least one beam, wherein the first report message further includes information related to the index of the beam based on the seventh message.

[0024] The first report message may include: the ID of the second TRP, the index of the beam that meets the SINR threshold of the first link, the ID of the third TRP, and the index of the beam that meets the SINR threshold of the second link.

[0025] The first report message may include only a common index of an index of at least one beam included in the fourth message and an index of at least one beam included in the seventh message.

[0026] Each of the second message and the first report message may be transmitted and received using a Radio Resource Control (RRC) signaling message.

[0027] When the first TRP and the second TRP are connected to the same base station, the first message may be sent using one of uplink control information (UCI), measurement report, or user equipment (UE) assistance information.

[0028] When the first TRP and the second TRP are connected to different base stations, the first message may be sent using a message based on a random access channel (RACH) access procedure.

[0029] Beneficial Effects

[0030] By using the apparatus and method according to the present invention, when a beam failure occurs in an MTRP environment, beam recovery can be performed while minimizing the impact on communications with other TRPs. In particular, when a single terminal communicates with multiple TRPs in an MTRP environment, it has the following advantages: the beam between the TRP where the beam failure occurs and the terminal is restored while minimizing the impact on the beams of other TRPs communicating with the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0032] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0033] Figure 3 is a block diagram illustrating a first exemplary embodiment of a communication node performing communications.

[0034] Figure 4a is a block diagram illustrating a first exemplary implementation of a transmit path.

[0035] Figure 4b is a block diagram illustrating a first exemplary implementation of a receive path.

[0036] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a system frame in a communication system.

[0037] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a subframe in a communication system.

[0038] Figure 7is a conceptual diagram illustrating a first exemplary embodiment of a time slot in a communication system.

[0039] Figure 8 is a conceptual diagram illustrating a first exemplary implementation of time-frequency resources in a communication system.

[0040] Fig. 9 is a signal flow diagram of the process of exchanging identifiers of three TRPs communicating with a terminal according to the present invention.

[0041] Fig.10 is a signal flow diagram of a process for notifying neighboring TRPs of a beam failure when the beam failure occurs according to the present invention.

[0042] Fig.11 is a signal flow diagram of a process for selecting an optimal beam index based on the index of a beam of a TRP where a beam failure occurs according to the present invention.

[0043] Fig.12 is a signal flow diagram of a process of delivering information about the index of beams satisfying a SINR threshold according to the present invention.

[0044] Fig.13 is a signal flow diagram of a process in which a TRP with beam failure selects a beam for beam recovery according to the present invention.

[0045] Fig.14 is a sequence diagram illustrating a beam failure recovery process in an MTRP CJT environment according to an exemplary embodiment of the present invention.

[0046] Fig.15 is a signal flow diagram according to an exemplary embodiment of the present invention, wherein Figures 9 to 13 All processes are combined and executed.

[0047] Fig.16 is a signal flow diagram for beam failure recovery according to the present invention in an MTRP NCJT environment.

[0048] Fig.17 is a signal flow diagram of beam failure recovery according to the present invention in an MTRP NCJT environment.

[0049] Fig.18 It is a flowchart of a process in which a neighboring TRP of a TRP having a beam failure selects an optimal beam for beam failure recovery according to the present invention in an MTRP NCJT environment.

[0050] Fig.19 is a signal flow diagram of a process in which a TRP in which a beam failure occurs selects an optimal beam for beam failure recovery based on information received from neighboring TRPs via a terminal according to the present invention in an MTRP NCJT environment.

[0051] Fig. 20 1 is a signal flow diagram of a process in which a terminal having a beam failure receives information for beam failure recovery from a neighboring TRP according to the present invention in an MTRP NCJT environment.

[0052] Fig.21 It is a signal flow diagram of a process of determining beam failure recovery at a terminal having beam failure according to the present invention in an MTRP NCJT environment.

[0053] Fig. 22 is a flow chart of a process for determining a beam to be used for beam failure recovery when a beam failure occurs according to the present invention in an MTRP NCJT environment.

[0054] Fig.23 is a flow chart of a process of performing beam failure recovery in an MTRP NCJT environment according to an exemplary embodiment of the present invention.

[0055] Fig.24 is a signal flow diagram of a process of performing beam recovery for a TRP with beam failure according to the present invention in an MTRP NCJT environment.

[0056] Fig.25 It is a signal flow diagram of a process of performing beam failure recovery on a terminal having a beam failure according to the present invention in an MTRP NCJT environment. DETAILED DESCRIPTION

[0057] Since the present invention can be variously modified and can have multiple forms, specific exemplary embodiments will be shown in the drawings and described in detail in the specific embodiments. However, it should be understood that it is not intended to limit the present invention to specific exemplary embodiments, but on the contrary, the present invention covers all modifications and alternative forms that fall within the spirit and scope of the present invention.

[0058] Relational terms such as first, second, etc. can be used to describe various elements, but these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, a first component can be named as a second component, and the second component can also be similarly named as the first component. The term "and / or" means any one or combination of multiple related and described matters.

[0059] In the present invention, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B". In addition, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0060] In the present invention, "(re)transmission" may refer to "transmission", "retransmission" or "transmission and retransmission", "(re)configuration" may refer to "configuration", "reconfiguration" or "configuration and reconfiguration", "(re)connection" may refer to "connection", "reconnection" or "connection and reconnection", and "(re)access" may refer to "access", "reaccess" or "access and reaccess".

[0061] When it is mentioned that a certain component is "coupled" or "connected" to another component, it should be understood that the certain component is directly "coupled" or "connected" to the other component, or another component may be provided therebetween. On the contrary, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it should be understood that no other component is provided therebetween.

[0062] The terms used in the present invention are only used to describe specific exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "including" or "having" are intended to indicate the presence of features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, but it should be understood that these terms do not exclude the presence or addition of one or more features, quantities, steps, operations, components, parts, or combinations thereof.

[0063] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those generally understood by those of ordinary skill in the art to which the present invention belongs. Terms commonly used in dictionaries and already in dictionaries should be interpreted as having meanings that match the contextual meanings in the art. In this specification, unless explicitly defined, terms are not necessarily interpreted as having formal meanings.

[0064] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate a comprehensive understanding of the present invention, the same reference numerals refer to the same elements in the description of the entire accompanying drawings, and repeated descriptions thereof will be omitted. Operations of the exemplary embodiments clearly described in the present invention and combinations of the exemplary embodiments, expansions of the exemplary embodiments, and / or variants of the exemplary implementations may be performed. Some operations may be omitted, and the sequence of operations may be changed.

[0065] Even when a method (e.g., transmission or reception of a signal) performed at a first communication node among communication nodes is described in an exemplary embodiment, a corresponding second communication node may perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when the operation of a user equipment (UE) is described, a base station corresponding thereto may perform an operation corresponding to the operation of the UE. Conversely, when the operation of a base station is described, a corresponding UE may perform an operation corresponding to the operation of the base station.

[0066] A base station may be referred to by various terms, such as node B, evolved node B, next generation node B (gNodeB), gNB, equipment, device, node, communication node, base transceiver station (BTS), radio remote head (RRH), transmission reception point (TRP), radio unit (RU), roadside unit (RSU), radio transceiver, access point, access node, etc. User equipment (UE) may be referred to by various terms, such as terminal, equipment, device, node, communication node, end node, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, on-board unit (OBU), etc.

[0067] In the present invention, signaling may be one of higher layer signaling, MAC signaling and physical (PHY) signaling, or a combination of two or more. A message for higher layer signaling may be referred to as a "higher layer message" or a "higher layer signaling message". A message for MAC signaling may be referred to as a "MAC message" or a "MAC signaling message". A message for PHY signaling may be referred to as a "PHY message" or a "PHY signaling message". Higher layer signaling may refer to the operation of sending and receiving system information (e.g., a master information block (MIB), a system information block (SIB)) and / or an RRC message. MAC signaling may refer to the operation of sending and receiving a MAC control element (CE). PHY signaling may refer to the operation of sending and receiving control information (e.g., downlink control information (DCI), uplink control information (UCI) or sidelink control information (SCI)).

[0068] In the present invention, "configuration of an operation (e.g., sending an operation)" may refer to configuration information (e.g., information element, parameter) required for the operation and / or signaling of information indicating the execution of the operation. "Configuration of an information element (e.g., parameter)" may refer to signaling of an information element. In the present invention, "signal and / or channel" may refer to a signal, a channel, or both a signal and a channel, and "signal" may be used to mean "signal and / or channel".

[0069] The communication network to which the exemplary embodiment is applied is not limited to the communication network described below, and the exemplary embodiment can be applied to various communication networks (e.g., 4G communication network, 5G communication network and / or 6G communication network). Here, "communication network" can be used interchangeably with the term "communication system".

[0070] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0071] like Figure 1As shown, the communication system 100 may include a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6. In addition, the communication system 100 may further include: a core network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (PDN gateway, P-GW), a mobility management entity (MME)). When the communication system 100 is a 5G communication (e.g., an NR system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc.

[0072] The plurality of communication nodes 110 to 130 may support communication protocols specified in the 3rd Generation Partnership Project (3GPP) standard (eg, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support the following technologies: code division multiple access (CDMA), wideband CDMA (WCDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiplexing (OFDM), filtered OFDM, cyclic prefix OFDM (CP-OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), orthogonal frequency division multiple access (OFDMA), single carrier FDMA (SC-FDMA), non-orthogonal multiple access (NOMA), generalized frequency division multiplexing (GFDM), filter bank multi-carrier (filter bank The communication nodes may include the following: multi-carrier (FBMC) technology, universal filtered multi-carrier (UFMC) technology, space division multiple access (SDMA) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0073] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0074] like Figure 2As shown, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network for performing communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. Each component included in the communication node 200 can communicate with each other when connected through a bus 270.

[0075] The processor 210 may execute a program stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which a method according to an embodiment of the present invention is executed. Each of the memory 220 and the storage device 260 may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0076] Reference again Figure 1 , the communication system 100 may include a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. The communication system 100 including the base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and the terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may be referred to as an "access network". Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell, and each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3 and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. In addition, the second terminal 130-2, the fourth terminal 130-4 and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. In addition, the fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5 and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. In addition, the first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1, and the sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

[0077] Here, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 may refer to a Node-B, an evolved Node-B (eNB), a gNB, an advanced base station (ABS), a high reliability base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multihop relay-base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (transmission point point (TP), transmission and reception point (TRP), etc.

[0078] Each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 may refer to user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability-mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, on-board unit (OBU), etc.

[0079] On the other hand, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can operate in the same frequency band or in different frequency bands. The multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can be connected to each other via an ideal backhaul or a non-ideal backhaul, and exchange information with each other via an ideal or non-ideal backhaul. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can be connected to the core network via an ideal or non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1 and 120-2 may transmit a signal received from the core network to a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6, and transmit a signal received from a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 to the core network.

[0080] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can support multiple-input multi-output (MIMO) transmission (for example, single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in unlicensed frequency bands, sidelink communication (for example, device-to-device (D2D) communication, proximity service (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operations corresponding to the following: operations of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and operations supported by the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 in a SU-MIMO manner, and the fourth terminal 130-4 may receive a signal from the second base station 110-2 in a SU-MIMO manner. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 in a MU-MIMO manner, and the fourth terminal 130-4 and the fifth terminal 130-5 may receive a signal from the second base station 110-2 in a MU-MIMO manner.

[0081] The first base station 110-1, the second base station 110-2 and the third base station 110-3 can send signals to the fourth terminal 130-4 in a CoMP transmission manner, and the fourth terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2 and the third base station 110-3 in a CoMP manner. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can exchange signals with the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 belonging to its cell coverage in a CA manner. Each of base stations 110-1, 110-2 and 110-3 can control the sidelink communication between the fourth terminal 130-4 and the fifth terminal 130-5, so the fourth terminal 130-4 and the fifth terminal 130-5 can perform sidelink communication under the control of the second base station 110-2 and the third base station 110-3, respectively.

[0082] On the other hand, a communication node that performs communication in a communication network may be configured as follows. Figure 3 The communication nodes shown may be Figure 2 A specific exemplary embodiment of a communication node is shown.

[0083] Figure 3 is a block diagram illustrating a first exemplary embodiment of a communication node performing communications.

[0084] like Figure 3 As shown, each of the first communication node 300a and the second communication node 300b can be a base station or a UE. The first communication node 300a can send a signal to the second communication node 300b. The transmission processor 311 included in the first communication node 300a can receive data (e.g., data unit) from the data source 310. The transmission processor 311 can receive control information from the controller 316. The control information may include at least one of system information, RRC configuration information (e.g., information configured by RRC signaling), MAC control information (e.g., MAC CE) or PHY control information (e.g., DCI, SCI).

[0085] The transmit processor 311 may generate data symbols by performing processing operations on data (e.g., encoding operations, symbol mapping operations, etc.). The transmit processor 311 may generate control symbols by performing processing operations on control information (e.g., encoding operations, symbol mapping operations, etc.). In addition, the transmit processor 311 may generate synchronization / reference symbols for synchronization signals and / or reference signals.

[0086] The Tx MIMO processor 312 may perform spatial processing operations (e.g., pre-coding operations) on data symbols, control symbols, and / or synchronization / reference symbols. The output (e.g., symbol stream) of the Tx MIMO processor 312 may be provided to a modulator (MOD) included in the transceivers 313a to 313t. The modulator may generate modulation symbols by performing processing operations on the symbol stream, and may generate signals by performing additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, up-conversion operations, etc.) on the modulation symbols. The signals generated by the modulators of the transceivers 313a to 313t may be transmitted through the antennas 314a to 314t.

[0087] The signal transmitted by the first communication node 300a may be received at the antenna 364a to the antenna 364r of the second communication node 300b. The signal received at the antenna 364a to the antenna 364r may be provided to a demodulator (DEMOD) included in the transceiver 363a to the transceiver 363r. The demodulator (DEMOD) may obtain samples by performing processing operations (e.g., filtering operations, amplification operations, down-conversion operations, digital conversion operations, etc.) on the signal. The demodulator may perform additional processing operations on the samples to obtain symbols. The MIMO detector 362 may perform MIMO detection operations on the symbols. The receiving processor 361 may perform processing operations (e.g., deinterleaving operations, decoding operations, etc.) on the symbols. The output of the receiving processor 361 may be provided to the data sink. 360 and controller 366. For example, data may be provided to data sink 360, and control information may be provided to controller 366.

[0088] On the other hand, the second communication node 300b can send a signal to the first communication node 300a. The transmission processor 368 included in the second communication node 300b can receive data (e.g., data unit) from the data source 367, and perform processing operations on the data to generate data symbols. The transmission processor 368 can receive control information from the controller 366, and perform processing operations on the control information to generate control symbols. In addition, the transmission processor 368 can generate reference symbols by performing processing operations on reference signals.

[0089] The Tx MIMO processor 369 may perform spatial processing operations (e.g., pre-coding operations) on data symbols, control symbols, and / or reference symbols. The output (e.g., symbol stream) of the Tx MIMO processor 369 may be provided to a modulator (MOD) included in the transceiver 363a to the transceiver 363t. The modulator may generate modulation symbols by performing processing operations on the symbol stream, and may generate signals by performing additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, up-conversion operations) on the modulation symbols. The signals generated by the modulators of the transceivers 363a to the transceivers 363t may be transmitted via the antennas 364a to the antennas 364t.

[0090] The signal transmitted by the second communication node 300b can be received at the antenna 314a to the antenna 314r of the first communication node 300a. The signal received at the antenna 314a to the antenna 314r can be provided to the demodulator (DEMOD) included in the transceiver 313a to the transceiver 313r. The demodulator can obtain samples by performing processing operations (e.g., filtering operations, amplification operations, down-conversion operations, digital conversion operations) on the signal. The demodulator can perform additional processing operations on the samples to obtain symbols. The MIMO detector 320 can perform MIMO detection operations on the symbols. The receiving processor 319 can perform processing operations (e.g., deinterleaving operations, decoding operations, etc.) on the symbols. The output of the receiving processor 319 can be provided to the data sink 318 and the controller 316. For example, data can be provided to the data sink 318, and control information can be provided to the controller 316.

[0091] Memory 315 and storage 365 may store data, control information and / or program codes. Scheduler 317 may perform scheduling operations for communications. Figure 3 The processors 311, 312, 319, 361, 368, 369 and the controllers 316 and 366 shown may be Figure 2 The processor 210 shown may be configured to execute the methods described in the present invention.

[0092] Figure 4a is a block diagram illustrating a first exemplary embodiment of a transmit path, Figure 4b is a block diagram illustrating a first exemplary implementation of a receive path.

[0093] like Figure 4a and Figure 4bAs shown, the transmission path 410 can be implemented in a communication node that transmits a signal, and the reception path 420 can be implemented in a communication node that receives a signal. The transmission path 410 may include: a channel coding and modulation block 411, a serial-to-parallel (S to P) block 512, an N-point inverse fast Fourier transform (N-point IFFT) block 413, a parallel-to-serial (P to S) block 414, a cyclic prefix (CP) adding block 415 and an up-converter (UC) 416. The reception path 420 may include a down-converter (DC) 421, a CP deletion block 422, an S to P block 423, an N-point FFT block 424, a P to S block 425 and a channel decoding and demodulation block 426. Here, N may be a natural number.

[0094] In the transmission path 410, the information bits may be input to the channel coding and modulation block 411. The channel coding and modulation block 411 may perform coding and decoding operations (e.g., low-density parity check (LDPC) coding and decoding operations, polar coding and decoding operations, etc.) and modulation operations (e.g., quadrature phase shift keying (OPSK), quadrature amplitude modulation (QAM), etc.) on the information bits. The output of the channel coding and modulation block 411 may be a modulation symbol sequence.

[0095] The S to P block 412 may convert the frequency domain modulation symbols into parallel symbol streams to generate N parallel symbol streams. N may be an IFFT size or an FFT size. The N-point IFFT block 413 may generate a time domain signal by performing an IFFT operation on the N parallel symbol streams. The P to S block 414 may convert the output (e.g., parallel signals) of the N-point IFFT block 413 into a serial signal to generate a serial signal.

[0096] The CP adding block 415 may insert the CP into the signal. The UC 416 may up-convert the frequency of the output of the CP adding block 415 to a radio frequency (RF) frequency. In addition, the output of the CP adding block 415 may be filtered in baseband before up-conversion.

[0097] The signal transmitted from the transmission path 410 may be input to the reception path 420. The operation in the reception path 420 may be the reverse operation of the operation in the transmission path 410. The DC 421 may down-convert the frequency of the received signal to the baseband frequency. The CP removal block 422 may remove the CP from the signal. The output of the CP removal block 422 may be a serial signal. The S to P block 423 may convert the serial signal into a parallel signal. The N-point FFT block 424 may generate N parallel signals by performing an FFT algorithm. The P to S block 425 may convert the parallel signal into a modulation symbol sequence. The channel decoding and demodulation block 426 may perform a demodulation operation on the modulation symbol, and may recover the data by performing a decoding operation on the result of the demodulation operation.

[0098] exist Figure 4a and Figure 4b In the present invention, discrete Fourier transform (DFT) and inverse DFT (IDFT) can be used to replace FFT and IFFT. Figure 4a and Figure 4b Each of the blocks (eg, components) in the embodiment may be implemented by at least one of hardware, software, or firmware. Figure 4a and Figure 4b Some blocks in the can be implemented by software, and other blocks can be implemented by hardware or a combination of hardware and software. Figure 4a and Figure 4b In the , a block can be subdivided into multiple blocks, multiple blocks can be integrated into one block, some blocks can be omitted, and blocks that support other functions can be added.

[0099] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a system frame in a communication system.

[0100] like Figure 5 As shown, the time resources in the communication system can be divided on a frame basis. For example, the system frame of the communication system can be configured continuously in the time domain. The length of the system frame can be 10 milliseconds (ms). The system frame number (SFN) can be set to one of #0 to #1023. In this case, 1024 system frames can be repeated in the time domain of the communication system. For example, the SFN of the system frame after system frame #1023 can be #0.

[0101] One system frame may include two half frames. The length of the half frame may be 5 ms. The half frame located at the start area of ​​the system frame may be referred to as "half frame #0", and the half frame located at the end area of ​​the system frame may be referred to as "half frame #1". One system frame may include 10 subframes. The length of one subframe may be 1 ms. The 10 subframes within one system frame may be referred to as subframe #0-subframe #9.

[0102] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a subframe in a communication system.

[0103] like Figure 6 As shown, a subframe may include n time slots, where n may be a natural number. Accordingly, a subframe may consist of one or more time slots.

[0104] Figure 7 is a conceptual diagram illustrating a first exemplary embodiment of a time slot in a communication system.

[0105] like Figure 7 As shown, a time slot may include one or more symbols. For example, Figure 7 One slot shown in may include 14 symbols. The length of the slot may vary according to the number of symbols included in the slot and the length of the symbol. Alternatively, the length of the slot may vary according to a parameter set.

[0106] The parameter set applied to the physical signal and channel in the communication system can be variable. The parameter set can be adjusted to meet various technical requirements of the communication system. In a communication system applying OFDM waveform technology based on cyclic prefix (CP), the parameter set may include subcarrier spacing and CP length (or CP type). Table 1 may show a first exemplary embodiment of a method for configuring a parameter set of a communication system based on CP-OFDM. Depending on the frequency band in which the communication system operates, at least some of the parameter sets in Table 1 may be supported. In addition, the communication system may support parameter sets not listed in Table 1.

[0107] [Table 1]

[0108]

[0109]

[0110] When the subcarrier spacing is 15kHz (e.g., μ=0), the length of the time slot may be 1ms. In this case, one system frame may include 10 time slots. When the subcarrier spacing is 30kHz (e.g., μ=1), the length of the time slot may be 0.5ms. In this case, one system frame may include 20 time slots.

[0111] When the subcarrier spacing is 60kHz (e.g., μ=2), the length of the time slot may be 0.25ms. In this case, one system frame may include 40 time slots. When the subcarrier spacing is 120kHz (e.g., μ=3), the length of the time slot may be 0.125ms. In this case, one system frame may include 80 time slots. When the subcarrier spacing is 240kHz (e.g., μ=4), the length of the time slot may be 0.0625ms. In this case, one system frame may include 160 time slots.

[0112] A symbol may be configured as a downlink (DL) symbol, a flexible (FL) symbol, or an uplink (UL) symbol. A time slot consisting only of DL symbols may be referred to as a "DL time slot", a time slot consisting only of FL symbols may be referred to as a "FL time slot", and a time slot consisting only of UL symbols may be referred to as a "UL time slot".

[0113] The slot format can be semi-statically configured by higher layer signaling (e.g., RRC signaling). Information indicating the semi-static slot format can be included in the system information, and the semi-static slot format can be configured to be cell-specific. In addition, the semi-static slot format can be further configured for each terminal by terminal-specific high-layer signaling (e.g., RRC signaling). The flexible symbols in the cell-specific slot format can be overwritten as downlink symbols or uplink symbols by terminal-specific high-layer signaling. In addition, the slot format can be dynamically indicated by physical layer signaling (e.g., a slot format indicator (SFI) included in the DCI). The semi-statically configured slot format can be overwritten by the dynamically indicated slot format. For example, the semi-statically configured flexible symbols can be overwritten by the SFI as downlink symbols or uplink symbols.

[0114] Reference signals may include a Channel State Information-Reference Signal (CSI-RS), a Sounding Reference Signal (SRS), a Demodulation-Reference Signal (DM-RS), and a Phase Tracking-Reference Signal (PT-RS). Channels may include a Physical Broadcast Channel (PBCH), a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Control Channel (PUCCH), a Physical Uplink Shared Channel (PUSCH), a Physical Sidelink Control Channel (PSCCH), and a Physical Sidelink Shared Channel (PSSCH). In the present invention, the control channel may refer to PDCCH, PUCCH or PSCCH, and the data channel may refer to PDSCH, PUSCH or PSSCH.

[0115] Figure 8 is a conceptual diagram illustrating a first exemplary implementation of time-frequency resources in a communication system.

[0116] like Figure 8 As shown, a resource consisting of one OFDM symbol on the time axis and one subcarrier on the frequency axis can be defined as a "resource element (RE)". A resource consisting of one OFDM symbol on the time axis and K subcarriers on the frequency axis can be defined as a "resource element group (REG)". A REG may include K REs. REG may be used as a basic unit for resource allocation in the frequency domain. K may be a natural number. For example, K may be 12. N may be a natural number. Figure 7 In the illustrated time slot, N may be 14. N OFDM symbols may be used as a basic unit for resource allocation in the time domain.

[0117] In the present invention, RB may refer to a common RB (CRB). Alternatively, RB may refer to a physical RB (PRB) or a virtual RB (VRB). In a communication system, CRB may refer to an RB that constitutes a set of continuous RBs (e.g., a common RB grid) based on a reference frequency (e.g., point A). A carrier and / or bandwidth part may be mapped to a common RB grid. That is, a carrier and / or bandwidth part may be configured with CRBs. An RB or CRB constituting a bandwidth part may be referred to as a PRB, and a CRB index may be appropriately converted to a PRB index within a bandwidth part.

[0118] Downlink data can be transmitted through PDSCH. The base station can send configuration information (e.g., scheduling information) of PDSCH to the terminal through PDCCH. The terminal can obtain the configuration information of PDSCH by receiving PDCCH (e.g., downlink control information (DownlinkControl Information, DCI)). For example, the configuration information of PDSCH may include the modulation coding scheme (MCS) used for sending / receiving PDSCH, the time resource information of PDSCH, the frequency resource information of PDSCH, and the feedback resource information of PDSCH. PDSCH may refer to the radio resources for sending and receiving downlink data. Alternatively, PDSCH may refer to the downlink data itself. PDCCH may refer to the radio resources for sending and receiving downlink control information (e.g., DCI). Alternatively, PDCCH may refer to the downlink control information itself.

[0119] The terminal may perform a monitoring operation on the PDCCH to receive the PDSCH sent from the base station. The base station may notify the terminal of configuration information for the PDCCH monitoring operation using a high-level message (e.g., a Radio Resource Control (RRC) message). The configuration information for the PDCCH monitoring operation may include control resource set (ControlResource Set, CORESET) information and search space information.

[0120] CORESET information may include PDCCH DMRS information, PDCCH precoding information, and PDCCH timing information, etc. PDCCH DMRS may be a DMRS used to demodulate PDCCH. PDCCH timing refers to an area where PDCCH may potentially exist, which means that it is an area where DCI can be transmitted. PDCCH timing may also be referred to as a PDCCH candidate. PDCCH timing information may include time resource information and frequency resource information for PDCCH timing. In the time domain, the length of the PDCCH timing may be indicated in symbols. In the frequency domain, the size of the PDCCH timing may be indicated in RB units (e.g., in PRB units or CRB units).

[0121] The search space information may include a CORESET identifier (ID) associated with the search space, a periodicity of PDCCH monitoring, and / or an offset of PDCCH monitoring. The periodicity and offset of PDCCH monitoring may each be indicated in units of time slots. In addition, the search space information may further include an index of a symbol at which the PDCCH monitoring operation starts.

[0122] The base station may configure a bandwidth part (Bandwidth Part, BWP) for downlink communication. The BWP may be configured differently for each terminal. The base station may notify the terminal of BWP configuration information using high-level signaling. High-level signaling may refer to a transmission operation of system information and / or a transmission operation of an RRC message. The number of BWPs configured for a single terminal may be one or more. The terminal may receive BWP configuration information from the base station and identify the configured BWP based on the received configuration information. When multiple BWPs are configured for downlink communication, the base station may activate one or more BWPs in the multiple BWPs. The base station may send configuration information of the activated BWP to the terminal using at least one of high-level signaling, a medium access control (MAC) control element (CE) or a DCI. The base station may perform downlink communication using the activated BWP. The terminal may identify the activated BWP by receiving configuration information from the base station and perform a downlink reception operation on the activated BWP.

[0123] On the other hand, in 5G NR, multi-transmission and reception point (MTRP) technology refers to a technology in which gNB uses physically separated multiple TRPs to communicate with terminals. MTRP technology helps solve the problem of reduced quality of service (QoS) of cell edge terminals far away from base stations, and alleviates inter-cell interference from base stations in different cells. In addition, it helps to provide an alternative communication path in a limited environment with a non-line-of-sight (NLOS) path in wireless communication technology using high frequency bands such as millimeter wave bands.

[0124] In the current 3GPP standard, MTRP technology is classified into a coherent joint transmission (CJT) scheme and a non-coherent joint transmission (NCJT) scheme. In the CJT scheme, TRPs collaborate in a synchronous manner based on a reliable backhaul link between base stations connected to the TRPs. On the other hand, in the NCJT scheme, scheduling, pre-coding matrix selection, modulation, and coding schemes are determined uncoordinatedly between multiple TRPs supporting a single terminal.

[0125] In order to support MTRP technology in the 5G NR standard, various aspects such as PDCCH, PUCCH and PUSCH enhancement, inter-cell operation and beam management for MTRP are being discussed. Regarding beam management in these aspects, an agreement has been reached on a method for performing beam indication for multiple beams to a terminal in an MTRP environment and a process for a terminal to receive multiple beams and report their performance.

[0126] However, most of the discussions so far have been limited to the basic configuration of the beam management process in the communication between multiple TRPs and the terminal in the MTRP environment, or to the signaling required to support beam management in the MTRP environment. However, there is still a lack of detailed procedures for the beam management process and consideration of beam failure situations in the MTRP environment. In particular, the situation where the terminal can no longer exchange information with the TRP that has experienced a beam failure in the MTRP environment has not been discussed. For example, in an environment where the terminal communicates with multiple TRPs, if the beam failure recovery process is performed independently by considering only the link between the terminal and the TRP where the beam failure occurred, the links between the terminal and other TRPs may not be considered, potentially resulting in poor performance on those links. Therefore, the beam selected as the best by the beam failure recovery process, focusing only on the link where the beam failure occurred, may not guarantee the best communication with other TRPs. Therefore, in the MTRP environment, if a beam failure occurs on a link between a TRP and a terminal, it may be necessary to define a beam failure recovery process that also takes into account links with other TRPs and the parameters required for such a process.

[0127] In addition, 3GPP is discussing various situations where MTRP should be considered. For example, it has been agreed that all intra-cell and inter-cell MTRP schemes specified in the unified TCI framework extension should be considered. In addition, it has been agreed that at least in the unified TCI framework extension for a single DCI-based MTRP, the existing TCI field of DCI format 1_1 / 1_2 is used to indicate multiple joint / DL / UL TCI states of a CC / BWP or CC / BWP set of a CC list. In addition, it has been agreed that further solutions for TCI status updates should be considered to extend the unified TCI framework for M-DCI-based MTRP. The above protocol does not provide specific methods for MTRP support.

[0128] In the 5G NR that has been standardized so far, the communication process using MTRP is supported to improve the performance and efficiency of MIMO. The CJT or NCJT scheme in the MTRP technology can be determined according to the environment of the cell where the current TRP exists, the backhaul link connectivity, etc. In addition, depending on which scheme is selected between the CJT and NCJT schemes in the MTRP technology, it can be determined whether multiple TRPs collaborate to support one terminal (CJT scheme) or each TRP independently supports one terminal (NCJT scheme).

[0129] Recently, a discussion on the scenario in which a terminal in an MTRP environment is equipped with multiple panels was started at the 3GPP standard meeting. When a terminal uses multiple panels, it can simultaneously form multiple receive beams for beams sent by different TRPs, thereby achieving efficient information reception. The present invention considers the scenario in which a multi-panel terminal communicates with multiple TRPs in an MTRP environment. Specifically, it solves the situation in which a terminal assigns one TRP to each of its panels (e.g., TRP A-UE panel A, TRP B-UE panel B, TRP C-UE panel C) and beam failure recovery must be performed when a beam failure occurs at one of the TRPs during communication.

[0130] The present invention can also be applied to other situations besides the above situation. For example, the terminal needs to measure the signal-to-interference-plus-noise ratio (SINR) of the signals received from all TRPs. In this case, multiple TRPs can be assigned to a single panel of the terminal, or multiple panels of the terminal can be assigned to a single TRP. The present invention can also be applied when the SINR of the signal received from the TRP is measured based on the relationship established between the panel of the terminal and the TRP. As described above, the terminal can have multiple panels, and one or more panels can be mapped to one or more TRPs. In this case, the TRP with activated beam failure detection (BFD) and the UE panel mapped to it can independently perform a beam failure recovery process, thereby selecting a beam through the process. When BFD is activated and beam failure recovery and beam selection are performed accordingly, the beam selected by the recovery process may not guarantee optimal performance from the perspective of the terminal, and the terminal receives multiple beams from different TRPs at the same time. In addition, although the beam selected by the beam failure recovery process is the beam that can show the best performance when only the link between the TRP and the terminal is considered, there is a possibility that it may be a beam that acts as a high interference beam from the perspective of other TRPs. This may lead to a situation where other TRPs need to perform beam failure recovery.

[0131] In the present invention, when a beam failure occurs on a communication link between a TRP and a terminal in an MTRP environment and a beam failure recovery process is initiated, the terminal may first identify the SINR of signals received from other TRPs communicating with it during the recovery process. The present invention proposes a beam failure recovery process in which the terminal or TRP considers the performance of the communication link between the terminal and other TRPs. The present invention provides a process for exchanging information (such as BFD activation information and information about beams with degraded performance from the perspective of other TRPs) via a backhaul (CJT scheme) or using a terminal as an intermediate repeater (NCJT scheme). In addition, the present invention proposes a beam failure recovery process to address the limitations of the existing MTRP environment in which each TRP operates independently without considering the performance of other TRPs.

[0132] In the following description, the present invention considers a scenario in an MTRP environment, where three TRPs (e.g., TRP A, TRP B, and TRP C) support a single terminal equipped with multiple panels. For simplicity, three TRPs will be used as an example. However, the present invention is also applicable to scenarios where two or more TRPs support a single terminal.

[0133] In the present invention, for a scenario in which a terminal is communicating with three TRPs and a beam failure (BF) occurs on a communication link between the terminal and TRP A, a process for recovering from BF is proposed in consideration of the performance of communication links between the terminal and TRP B and TRP C. In addition, although the operation according to the present invention will be described assuming a downlink environment, the present invention can also be extended to be applied to an uplink environment.

[0134] Specifically, the present invention describes a process for delivering information about a TRP with a beam failure to other TRPs communicating with a terminal in CJT and NCJT environments. In addition, the present invention describes a process in which a terminal, during beam failure recovery using a TRP with a beam failure, identifies changes in the SINR of a corresponding beam formed by a failed TRP, which are measured based on signals received from other TRPs. In addition, the present invention describes a final beam selection process taking into account the SINR measured for other TRPs.

[0135] First, it can be assumed that a beam failure occurs on a beam link between TRP A and UE panel A of a terminal with multiple panels. In addition, it can be assumed that the terminal establishes a communication link between TRP B and UE panel B and between TRP C and UE panel C. Under these assumptions, TRP A may need to perform beam failure recovery with UE panel A of the terminal. Therefore, TRP A can deliver information about beam failure to TRP B and TRP C. TRP A can identify the SINR between the terminal and TRP B and TRP C for the index of the beam formed for UE panel A. For example, the terminal or TRP B can measure the SINR between TRP B and the terminal, and the terminal or TRP B can report (or forward) information about the SINR directly to TRP A. Similarly, the terminal or TRP C can measure the SINR between TRP C and the terminal, and the terminal or TRP C can report (or forward) information about the SINR directly to TRP A.

[0136] Based on the SINR between TRP B and the terminal and the SINR between TRP C and the terminal, TRP A can identify the SINR of the communication link between TRP B and UE panel B and between TRP C and UE panel C, respectively. Then, the index of the beam of TRP A that meets the SINR threshold of the communication link between TRP B and UE panel B can be delivered from TRP B to TRP A. Similarly, the beam index of TRP A that meets the SINR threshold of the communication link between TRP C and UE panel C can be delivered from TRP C to TRP A. Accordingly, TRP A can select the beam with the highest SINR on the communication link between itself and the terminal from the indexes of the beams delivered from TRP B and TRP C. If the above process is performed in a CJT environment, information transfer between TRPs can be performed via the backhaul, and if the above process is performed in an NCJT environment, information transfer between them can be performed via the terminal.

[0137] In the method proposed in the present invention, the information transfer scheme can vary depending on whether all TRPs are connected to the same base station or different base stations. For example, when TRP A, TRP B and TRP C are connected to the same base station, all TRPs can utilize the RRC signaling scheme. On the other hand, when at least one of TRP A, TRP B and TRP C is connected to another base station, it can be assumed that the terminal is RRC connected to the base station connected to TRP A, because the terminal can only be RRC connected to one base station. In this case, the terminal can be considered to be multi-connected to the base station connected to TRP B and TRP C through signaling radio bearer 3 (SRB3). The terminal and the base station connected to TRP B and TRP C can exchange information such as SN RRC reconfiguration, SN RRC reconfiguration completion, SN measurement report and SN UE assistance information through SRB3.

[0138] (1) Beam Fault Recovery Process in MTRP CJT Environment

[0139] In the present invention, the terms "terminal" and "UE" are used interchangeably. A terminal may be understood as a type of UE, and vice versa. A UE or terminal may include Figure 2 As another example, except that Figure 2 In addition to the components described in the above, the UE or terminal may have additional components. For example, the UE or terminal may further include various sensors, power supply devices and / or interface devices for interfacing with other external devices. When the terminal or UE according to the present invention includes Figure 2 When at least some of the components described in the embodiment of the present invention are included in the UE panel, the UE panel may be included in the transceiver 230. Accordingly, the transceiver 230 may perform configuration and operation for establishing a communication link with the TRP using multiple UE panels.

[0140] The TRP described below may also include Figure 2 As another example, except that Figure 2 In addition to the components described in, the TRP may include other components. For example, each of the TRPs may further include a component for establishing a backhaul link with a base station and / or at least one backhaul link for directly connecting to another TRP.

[0141] The present invention assumes that three TRPs (e.g., TRP A, TRP B, and TRP C) support an environment of a single terminal with multiple panels in an MTRP environment. In this case, consider a case where a beam failure occurs on a communication link between TRP A and UE panel A and beam failure recovery is performed. Figures 9 to 13 The following description assumes a CJT environment.

[0142] In the MTRP environment according to the present invention, since the terminal communicates with multiple TRPs, there may be a situation where a beam failure occurs only for a specific TRP instead of all TRPs. In this case, if the terminal independently performs a beam failure recovery process with the TRP where the beam failure occurs, the terminal simultaneously communicates with other TRPs where the beam failure does not occur, so performance degradation may occur on the communication link previously established with other TRPs.

[0143] In order to prevent such performance degradation, when beam failure recovery is performed between a TRP and a terminal, the method according to the present invention takes into account the communication performance between other TRPs and the terminal. Therefore, even if a beam failure occurs in one TRP, information on the beam failure in the TRP needs to be sent to other TRPs, and the beam failure recovery process is performed in consideration of the communication performance of other TRPs.

[0144] Accordingly, the following description Fig. 9 It may correspond to a process in which TRP A, TRP B, and TRP C communicating with a public terminal recognize each other's TRP IDs via a backhaul between TRPs or between base stations connected to the TRPs to support a single public terminal.

[0145] In addition, the following will describe Fig.10 It may correspond to a process in which TRP A sends information about beam failure occurring on the communication link established between it and UE panel A to TRP B and TRP C via a backhaul between TRPs or between base stations connected to the TRPs.

[0146] The following will describe Fig.11 It may correspond to a process in which TRP A transmits the index of its own candidate beam to be used in the beam failure recovery process with UE panel A to TRP B and TRP C via the backhaul between TRPs or between base stations connected to TRPs, and TRP B and TRP C respectively measure the SINR of the communication link established with UE panel B and UE panel C with reference to the candidate beam of TRP A. The following will describe Fig.12 This may correspond to a process in which TRP B and TRP C are based on Fig.11The measured SINR of the candidate beams of TRP A identified in the process is used to select the index of the beam of TRP A having an SINR equal to or higher than its SINR threshold, and then information about the selected beam index is sent to TRP A via a backhaul between TRPs or between base stations connected to TRPs. Finally, the following will describe Fig.13 can correspond to a process in which TRP A is Fig.12 The process selects the beam with the highest SINR among the beams indicated by the indexes received from TRP B and TRP C.

[0147] In conclusion, Fig. 9 and Fig.10 may correspond to a process in which TRP A notifies TRP B and TRP C of information about beam failure on the communication link between TRP A and UE Panel A, and Fig.11 and Fig.12 It can correspond to a process in which, among the indices of candidate beams formed by TRP A and UE panel A, TRP B and TRP C select the index of the beam of TRP A that meets the SINR threshold of the communication link previously established between them and UE panel B and UE panel C, and deliver information about the selected beam index to TRP A. Fig.13 It can correspond to a process in which TRP A, where a beam failure occurs, selects the best beam by considering the performance of its own communication link and the performance of the communication links between other TRPs and the terminal, so as to ensure reliable communication for all TRPs that communicate with the terminal in the future when performing the beam failure recovery process.

[0148] Hereinafter, a more detailed description will be given with reference to the accompanying drawings.

[0149] Fig. 9 is a signal flow diagram of the process of exchanging identifiers of three TRPs communicating with a terminal according to the present invention.

[0150] like Fig. 9 As shown, TRP A 901, TRP B 902, and TRP C 903 are shown, and TRPs 901 to 903 may be TRPs that communicate with a terminal 911. In addition, it may be assumed that a terminal has three or more different panels so that it can communicate with different TRPs 901 to 903. For example, it may be assumed that the terminal 911 communicates with TRP A 901 using panel A (not shown), communicates with TRP B 902 using panel B (not shown), and communicates with TRP C 903 using panel C (not shown).

[0151] As described above, TRP 901 to TRP 903 according to the present invention can be connected via a backhaul between TRPs or between base stations connected to TRPs. Each of TRP 901 to TRP 903 can know in advance that terminal 911 is communicating with other TRPs. Therefore, TRP 901 to TRP 903 may need to know which TRPs terminal 911 is communicating with. According to an exemplary embodiment of the present invention, an MTRP CJT environment is assumed. Therefore, communication between TRPs can be performed directly, or via a backhaul between TRPs through at least one base station.

[0152] In step S910a, TRP A 901 communicating with terminal 911 may exchange a TRP identifier (ID) with TRP B 902, which is another TRP communicating with terminal 911 via a direct connection or a backhaul connected through a base station. In other words, in step S910a, TRP A 901 may transmit information about its TRP ID to TRP B 902 via a direct connection or a backhaul connected through a base station. In addition, in step S910a, TRP A 901 may receive information about the TRP ID of TRP B from TRP B 902 using the backhaul.

[0153] In addition, in step S910b, TRP A 901 communicating with the terminal 911 may exchange TRP IDs with TRP C 903, which is another TRP communicating with the terminal 911 via a backhaul connected directly or through a base station. In other words, in step S910b, TRP A 901 may transmit information about its TRPID to TRP C 903 via a backhaul connected directly or through a base station. In addition, in step S910b, TRP A 901 may receive information about the TRPID of TRP C from TRP C 903 using the backhaul.

[0154] exist Fig. 9 In the example, the form of sequentially executing steps S910a and S910b is illustrated. However, in an actual implementation, step S910a and step S910b may be executed simultaneously. As another example, in an actual implementation, step S910b may be executed first, and step S910a may be executed later.

[0155] About Fig. 9 The information of TRP ID exchanged between TRPs described in the description can be as illustrated in Table 2 below.

[0156] [Table 2]

[0157]

[0158] On the other hand, when a beam failure occurs on the communication link between a specific TRP and terminal 911, the Fig. 9 The process of exchanging TRP ID information between TRPs. For example, a specific TRP can inform other TRPs of the information that a beam failure has occurred. In addition, the specific TRP where the beam failure occurred can use the TRP ID to send and receive necessary parameters during the beam failure recovery process. Fig. 9 The process in considers a CJT environment in which TRPs are connected via a backhaul between TRPs or between base stations connected to them, but it is also possible to consider a situation in which TRP A 901, TRP B 902 and TRP C 903 exchange their TRP IDs via terminal 911 in an NJCT environment and then establish a backhaul between TRPs or between base stations connected to the TRPs.

[0159] Described above Fig. 9 The exemplary embodiment may be used in combination with at least one of the other exemplary embodiments described below.

[0160] Fig.10 is a signal flow diagram of a process for notifying neighboring TRPs of a beam failure when the beam failure occurs according to the present invention.

[0161] like Fig.10 As shown, TRP A 901, TRP B 902, TRP C 903 and terminal 911 are as shown above. Fig. 9 As described in the above Fig. 9 The CJT environment described in the following Fig.10 process.

[0162] In step S1010, the terminal 911 may identify that a beam failure occurs on a communication link between TRP A and UE panel A. For example, if the number of beam failure instances (BFIs) exceeds the maximum allowed number of communication links established between the terminal 911 and a particular TRP, a beam failure may occur when the terminal 911 declares a beam failure. Therefore, the terminal 911 may be in a situation where a beam failure recovery process needs to be performed. In other words, the occurrence of a beam failure may correspond to a situation where BFI_COUNTER>=beamFailureInstanceMaxCount.

[0163] Here, BFI indicates a condition where a block error rate (BLER) is equal to or greater than a certain threshold, and a count value may be increased by 1 for each BFI. If the count value does not increase within a certain time after the count value is increased by 1, the BFI_COUNTER may be reset to zero (0). When the BFI_COUNTER is reset as described above, it may be interpreted that the BFI no longer occurs.

[0164] If a beam failure occurs as described above, the terminal 911 may transmit a beam failure recovery request signal (or message) to the TRP A 901 in step S1020. The beam failure recovery request signal (or message) may transmit the beam failure recovery request information to the TRP A 901 through the BeamFailureRecoveryConfig including information such as rach-ConfigBFR, rsrp-ThresholdSSB and / or candidateBeamRSList of RRC signaling.

[0165] TRP A 901 may attempt beam failure recovery based on the beam failure recovery request signal received from the terminal 911. In the present invention, before attempting beam failure recovery, TRP A 901 may first send information related to beam failure to other TRPs via the backhaul at step S1030 so as to consider the performance of the communication link between the other TRPs and the terminal. In this case, Fig. 9 As described in , TRP A 901 may pre-store information about other TRPs 902 and TRP 903 that can communicate with the terminal 911. Therefore, TRP A 901 may set a beam failure detection (BFD) indicator that notifies the terminal 911 of a beam failure to "1", and transmit information about the identifier TRP A_ID of TRP A 901 to neighboring TRPs 902 and TRP 903 via a backhaul. In this case, a backhaul directly connected between TRPs or a backhaul connected through a base station may be used.

[0166] Fig.10 Assume that three TRPs are Fig. 9 Therefore, in step S1030, TRPA 901 may send a BFD indicator and TRP A_ID to TRP B 902 and TRP C 903. When only TRP B 902 or only TRP C 903 exists as a TRP for communicating with terminal 911 in addition to TRP A 901, a BFD indicator and TRP A_ID may be sent only to the corresponding TRP. If, in addition to TRP A 901, Fig.10If at least one other TRP not shown in the figure exists as a TRP communicating with the terminal 911, a BFD indicator and TRP A_ID may be sent to the corresponding TRP in the same manner as TRP B 902 and TRP C 903.

[0167] As an example of modification of the present invention, in the process of notifying TRP B 902 and TRP C 903 of the beam failure occurring in TRP A 901, an indicator having a different form from the BFD indicator may be sent. For example, the occurrence of the beam failure may be notified by a beam failure detection field (e.g., beam failure detection = enumeration {ON, OFF} or enumeration {TRUE, FALSE}) within RRC signaling. The TRP ID and the BFD indicator may be sent by utilizing a backhaul between TRPs or between base stations connected to the TRPs.

[0168] The information sent by TRP A to other TRPs based on beam failure can be as illustrated in Table 3 below.

[0169] [Table 3]

[0170]

[0171]

[0172] After receiving information about the beam failure occurring in TRP A 901 through the above process, TRP B 902 and TRP C 903 may prepare to measure the SINR of the communication links established between them and the terminal, which is affected by the candidate beams formed by TRP A and UE panel A during the beam failure recovery process.

[0173] On the other hand, the above described Fig.10 The exemplary embodiments described above may be Fig. 9 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0174] Fig.11 is a signal flow diagram of a process for selecting an optimal beam index based on the index of a beam of a TRP where a beam failure occurs according to the present invention.

[0175] like Fig.11 As shown, TRP A 901, TRP B 902, TRP C 903 and terminal 911 are as shown above. Fig. 9 and Fig.10 As described in the above Fig. 9 and Fig.10 The CJT environment described in the following Fig.11 process.

[0176] Fig.11 It may correspond to the process after a beam failure occurs between TRP A 901 and UE panel A and terminal 911 requests beam failure recovery from TRP A 901. Therefore, TRP A 901 may need to find the best beam through the beam failure recovery process with UE panel A. In the present invention, TRP A 901 may perform beam failure recovery by considering neighboring TRPs during beam failure recovery with UE panel A.

[0177] In step S1110, TRP A 901 may send the index of the candidate beam formed by TRP A 901 for searching for the best beam together with the terminal 911 to other TRPs (e.g., TRP B 902 and TRP C 903) via the backhaul connected between TRPs or the backhaul between base stations connected to the TRPs.

[0178] Each of TRP B 902 and TRP C 903 that receives the index of the candidate beam of TRP A 901 from TRP A 901 in step S1110 may determine the SINR of the communication link established with the terminal 911 for each candidate beam of TRP A 901.

[0179] The beam index sent by TRP A 901 to TRP B 902 and TRP C 903 in step S1110 may be sent via a backhaul directly connected between TRPs or a backhaul between base stations connected to the TRPs through a candidateBeamRSList parameter in the signaling. As another example, the beam index sent by TRP A 901 to TRP B 902 and TRP C 903 in step S1110 may be sent using a parameter newly defined according to the present invention as a beam index for sending TRP A 901. Even in this case, the beam index of TRP A 901 may be sent via a backhaul directly connected between TRPs or a backhaul between base stations connected to the TRPs.

[0180] In step S1120a, TRP B 902 may receive the SINR reported by terminal 911 to TRP B 902 by measuring the channel between terminal 911 and TRP B 902. Based on this, in step S1120a, TRP B 902 may determine the SINR of the communication link with UE panel B of terminal 911. In step S1120a, TRP B 902 may select the index of the beam of TRP A 901 that satisfies its own SINR threshold (i.e., the minimum SINR that needs to be guaranteed for reliable communication without beam failure).

[0181] In addition, at step S1120b, TRP C 903 may receive the SINR reported by terminal 911 to TRP C 903 by measuring the channel between terminal 911 and TRP C 903. Based on this, at step S1120b, TRP C 903 may determine the SINR of the communication link with UE panel C of terminal 911. At step S1120b, TRP C 903 may select the index of the beam of TRP A 901 that satisfies its own SINR threshold (i.e., the minimum SINR that needs to be guaranteed for reliable communication without beam failure).

[0182] As above Fig. 9 As stated in Fig.11 Step S1120a and step S1120b may also be performed simultaneously. As another example, step S1120a and step S1120b may be performed in the same manner as Fig.11 The steps 1120a and 1120b are performed in the reverse order of the order shown, that is, step S1120b is followed by step S1120a. In this case, the SINR between TRP B 902 and terminal 911 and the SINR between TRP C 903 and terminal 911 of the beam index sent by TRP A 901 to TRP B 902 and TRP C 903 can be measured as shown in Table 4.

[0183] [Table 4]

[0184] Beam index of TRP A SINR measured for TRP B SINR measured for TRP C Beam Index = 1 SINR_65 SINR_65 Beam Index = 2 SINR_70 SINR_75 Beam Index = 3 SINR_80 SINR_60 Beam Index = 4 SINR_82 SINR_75 Beam Index = 5 SINR_85 SINR_80

[0185] In this case, the base station may dynamically set the SINR threshold according to the considered situation. It may be assumed that the SINR threshold of TRP B 902 is SINR_75, and the SINR threshold of TRP C 903 is SINR_70. In this case, the indexes of the beams of TRP A 901 that meet the threshold of TRP B 902 may be beam index 3, beam index 4, and beam index 5. In addition, the indexes of the beams of TRP A 901 that meet the threshold of TRP C 903 may be beam index 2, beam index 4, and beam index 5. This may mean that even if TRP A 901 of terminal 911 and UE panel A communicate later using the corresponding beam indexes, beam failure may not occur for the communication links established by TRP B 902 and TRP C 903 with UE panel B and UE panel C, respectively.

[0186] According to the above method, a candidate group of indexes of beams for which beam failure may not occur for all TRPs can be first identified based on the SINR threshold. Then, a process of finding the best beam from the candidate group can be performed.

[0187] exist Fig.11In the embodiment, the performance of each beam index is measured by considering only SINR. However, the exemplary embodiment can also be extended to a method of measuring the performance of each beam index by determining the reliability of the communication link by utilizing other criteria or by combining and considering multiple criteria. For example, the best beam can be selected by considering the delay requirement of terminal 911 or the mobility of terminal 911.

[0188] If the latency requirement of the terminal 911 is considered, a beam that supports higher performance in terms of user-experienced data rate may be selected. As another example, if the mobility of the terminal 911 is considered, a beam that can transmit data to the terminal 911 over a longer period of time based on the UE mobility or trajectory may be selected. As another example, when the reliability of the channel is considered, a method of selecting a beam with the smallest change in the measured SINR is also possible.

[0189] On the other hand, the above described Fig.11 The exemplary embodiments described above may be Fig. 9 and Fig.10 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0190] Fig.12 is a signal flow diagram of a process of delivering information about the index of beams satisfying a SINR threshold according to the present invention.

[0191] like Fig.12 As shown, TRP A 901, TRP B 902, TRP C 903 and terminal 911 are as shown above. Figures 9 to 11 As described in the above Figures 9 to 11 The CJT environment described in the following Fig.12 process.

[0192] Fig.12 The above described Fig.11 Each of TRP B 902 and TRP C 903 in the state selects the index of the beam of TRP A 901 having an SINR greater than or equal to the SINR threshold. Therefore, TRP B 902 and TRP C 903 can each obtain the index of the beam of TRP A 901 having an SINR greater than or equal to the SINR threshold.

[0193] In step S1210, TRB B 902 may send information about the index of the beam of TRP A 901 to TRP A 901, and the index of the beam may ensure communication through a communication link with terminal 911 (e.g., a communication link established between TRP B 902 and UE panel B of terminal 911).

[0194] In step S1220, TRB C 903 may send information about the index of the beam of TRP A 901 to TRP A 901, and the index of the beam may ensure communication through a communication link with terminal 911 (eg, a communication link established between TRP C 903 and UE panel C of terminal 911).

[0195] Using Table 4 and the thresholds of TRP B 902 and TRP C 903 at the bottom of Table 4, the indexes of beams of TRP A 901 that meet the threshold of TRP B 902 can be beam index 3, beam index 4, and beam index 5, and the indexes of beams of TRP A 901 that meet the threshold of TRPC 903 can be beam index 2, beam index 4, and beam index 5.

[0196] Accordingly, in step S1210, TRB B 902 may send beam index 3, beam index 4, and beam index 5 to TRP A 901 via the backhaul. In addition, in step S1220, TRB C 903 may send beam index 2, beam index 4, and beam index 5 to TRP A 901 via the backhaul.

[0197] exist Fig.12 In the description of, the case where the beam index is transmitted in the order of step S1210 and step S1220 has been described as an example. However, depending on the implementation method and the delay time for obtaining the SINR in each TRP, step S1210 and step S1220 may be performed in the reverse order. As another example, step S1210 and step S1220 may be performed simultaneously.

[0198] like Fig.12 The beam index received by TRP A 901 from TRP B 902 and TRP C 903 described in can be as illustrated in Table 5 below.

[0199] [Table 5]

[0200] Information delivered TRP B → TRP A Beam index = 3,4,5 TRP C → TRP A Beam index = 2, 4, 5

[0201] On the other hand, the above described Fig.12 The exemplary embodiments described above may be Figures 9 to 11 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0202] Fig.13 is a signal flow diagram of a process in which a TRP with beam failure selects a beam for beam recovery according to the present invention.

[0203] like Fig.13As shown, TRP A 901, TRP B 902, TRP C 903 and terminal 911 are as shown above. Figures 9 to 12 As described in the above Fig. 9 and Fig.12 The CJT environment described in the following Fig.13 process.

[0204] Fig.13 It is shown that when selecting a beam to be used for communication in TRP A901 where a beam failure occurs, the optimal beam index can be selected by considering the performance of the communication link between terminal 901 and other TRPs 902 and TRP 903 and the performance of the communication link between TRP A901 and terminal 911.

[0205] To this end, TRPA 901 may obtain the SINR of the corresponding candidate beam in advance together with UE panel A of terminal 911. The SINR for the corresponding candidate beam index received by TRPA 901 from terminal 911 may be exemplified in Table 6 below.

[0206] [Table 6]

[0207] Beam Candidate Set SINR of TRP A Beam Index = 1 SINR_95 Beam Index = 2 SINR_80 Beam Index = 3 SINR_100 Beam Index = 4 SINR_70 Beam Index = 5 SINR_75

[0208] In addition, TRP A901 can be Fig.12 The process receives the index of the beam that meets the SINR threshold from TRP B 902 and TRP C 903 in advance. Fig.12 As described in, TRB B 902 can send beam index 3, beam index 4 and beam index 5 to TRP A 901 via the backhaul, and TRB C 903 can send beam index 2, beam index 4 and beam index 5 to TRP A 901 via the backhaul.

[0209] TRP A 901 may determine the index of the beam received from TRP B 902 and TRP C 903 and the index of the beam based on the SINR measured between TRP A 901 and the terminal 911. When there are a total of 5 beams from beam index 1 to beam index 5, the beam index selectable based on the index of the beam received from TRP B 902 and TRP C 903 and the SINR between TRP A 901 and the terminal 911 may be as shown in Table 7 below.

[0210] [Table 7]

[0211] Beam Candidate Set SINR of TRP A TRP B TRP C Beam Index = 4 SINR_70 Get Satisfied Get Satisfied Beam Index = 5 SINR_75 Get Satisfied Get Satisfied

[0212] In step S1310, TRPA 901 may select the index of the beam to be finally used with UE panel A of terminal 911 based on Table 7. Based on the above Table 7, TRPA 901 may select the beam corresponding to beam index 5 as the best beam. In other words, TRPA 901 may select the index of the beam having the maximum SINR among the beams of TRPA 901 in Table 7.

[0213] On the other hand, the above described Fig.13 The exemplary embodiments described above may be Figures 9 to 12 The exemplary embodiments and / or at least one of the exemplary embodiments described below may be used in combination.

[0214] According to the above description Figures 9 to 13 In an exemplary embodiment, when TRP A 901 performs a beam failure recovery process together with UE panel A, TRP A can receive an index of a beam of TRP A 901 that guarantees that its communication performance can reach a certain level or higher from neighboring TRPs (i.e., TRP B 902 and TRP C 903). In this case, information about the index of the beam of TRP A 901 can be received via a backhaul between TRPs or a backhaul between base stations connected to the TRPs. Then, TRPA 901 can select the best beam among the beams that can be configured using terminal 911.

[0215] Fig.14 is a sequence diagram illustrating a beam failure recovery process in an MTRP CJT environment according to an exemplary embodiment of the present invention.

[0216] like Fig.14 As shown, in step 1410, when a beam failure recovery request is received from the terminal 911 based on the occurrence of the beam failure, the TRP A 901 may transmit information about the beam failure to other TRPs (i.e., TRP B 902 and TRP C 903) communicating with the terminal 911. In this case, the TRP A 901 may transmit its own TRP ID together to notify the TRP B 902 and TRP C 903 of the TRP in which the beam failure occurs. In addition, the TRP A 901 may notify the TRP B 902 and TRP C 903 of the index of the candidate beam formed between the TRP A 901 and the terminal 911.

[0217] In step 1420, each of TRP B 902 and TRP C 903 may receive an SINR corresponding to the index of the candidate beam based on the information about the beam failure and the index of the candidate beam formed by TRP A 901 and the terminal 911 received in step S1410. Then, each of TRP B 902 and TRP C 903 may transmit to TRP A 901 the index of the beam having an SINR greater than or equal to the threshold among the SINRs received from the terminal 911.

[0218] In step 1430, TRP A 901 may receive the SINR of the candidate beams formed between TRP A 901 and terminal 911 from terminal 911. In step 1420, TRP A 901 may select the index of the beam having the highest SINR among the candidate beams that can be used in common by the TRPs based on the indices of the beams received from TRP B 902 and TRP C 903, respectively, and the SINR received from terminal 911.

[0219] Fig.15 is a signal flow diagram according to an exemplary embodiment of the present invention, wherein Figures 9 to 13 All processes are combined and executed.

[0220] therefore, Fig.15 As shown above in Figures 9 to 13 The TRP A 901, TRP B 902, TRP C 903, and terminal 911 described in the figure may correspond to a case where a CJT environment is assumed. Since a CJT environment is assumed, each of TRPs 901 to 903 may send / receive data between TRPs 901 to 903 via a backhaul between TRPs and / or a backhaul with at least one base station.

[0221] Fig.15 Steps S1510a and S1510b shown in FIG. 1 may be a process for exchanging TRP IDs between TRP 901 to TRP 903, as described above in Fig. 9 Step S1520 may be a step for detecting a beam failure in terminal 911, i.e. Fig.10 Step S1530 and step S1540 may correspond to step S1020 and step S1030, respectively. In step S1020, terminal 911 sends a beam failure recovery request to TRP A 901. In step S1030, TRP A 901 sends its TRP ID and beam failure detection (BFD) indicator to neighboring TRPs 902 and 903, as shown in FIG. Fig.10 Described in .

[0222] Step S1550 may correspond to Fig.11 In step S1110 shown in FIG. 1 , TRP A 901 sends the index of the candidate beam configured together with terminal 911 for beam failure recovery to neighboring TRP 902 and TRP 903, and steps S1560a and S1560b may correspond to Fig.11 Steps S1120a and S1120b are shown, where TRP B 902 and TRP C 903 each select the index of the beam whose SINR is greater than or equal to the threshold.

[0223] Step S1570 and step S1580 may correspond to Fig.12 , wherein TRP B 902 and TRP C 903 each send to TRP A 901 the index of the beam whose SINR is greater than or equal to the threshold.

[0224] Step S1590 may correspond to Fig.13 In the step, TRP A 901 and terminal 911 jointly select the best beam for beam failure recovery.

[0225] exist Fig.15 In the exemplary embodiment of Figures 9 to 13 All processes of the exemplary embodiment of the present invention use a signal flow to describe the beam failure recovery process in a CJT environment. However, Figures 9 to 13 The exemplary embodiments can be used with Fig.15 The order shown is performed differently, and Figures 9 to 13 Some of the exemplary embodiments may be implemented as not being performed.

[0226] (2) Beam Failure Recovery Process in MTRP NCJT Environment

[0227] The present invention described below will describe the beam failure recovery process in the MTRP NCJT environment. In the MTRP NCJT environment, it can be assumed that three TRPs (e.g., TRP A, TRP B, and TRP C) support a single terminal with multiple panels, similar to the MTRP CJT environment described above. In addition, a case where a beam failure occurs on the communication link between TRP A of the terminal and UE panel A of the terminal and beam failure recovery is performed will be described. In addition, the following description Figures 16 to 22 Assume NCJT environment.

[0228] Since the terminal communicates with multiple TRPs in the MTRP environment, there may be a situation where beam failure occurs only for a specific TRP instead of all TRPs. In this case, if the terminal performs the beam failure recovery process independently with the TRP where the beam failure occurs, since the terminal simultaneously communicates with other TRPs that do not have the beam failure, performance degradation may occur on the communication links of other TRPs that have been previously established.

[0229] To prevent this situation, when performing beam failure recovery between a TRP and a terminal, the communication performance between other TRPs and the terminal needs to be considered. In the present invention, when a beam failure occurs in a specific TRP, information indicating that a beam failure has occurred is sent to other TRPs and a process of performing beam failure recovery considering the communication performance of other TRPs will be described.

[0230] Since synchronization between TRPs is not possible in the MTRP NCJT environment, Figures 9 to 13 The information transmitted and received via the backhaul between the TRP or the base stations connected to the TRP can be transmitted and received by utilizing the terminal as an intermediate repeater instead of the backhaul as described below. Figures 16 to 22 In the process of sending and receiving via the terminal. Specifically, in the NCJT environment, a process is provided for a TRP to send TRP ID, BFD indicator and information about the index of the beam to other TRPs via the terminal. This information has been described as being sent and received via the backhaul between the TRP or the base stations connected to the TRP in the CJT environment.

[0231] Described below Fig.16 Assume that a beam failure occurs on a communication link established between TRP A among TRP A, TRP B, and TRP C communicating with the terminal and UE panel A of the terminal. In this case, Fig.16 It can correspond to the process in which the terminal notifies TRP B and TRP C of information about the TRP ID of TRP A and information about the beam failure of TRP A.

[0232] Fig.17 It may correspond to a process for observing the influence of the candidate beam formed by TRP A for the UE panel A of the terminal on the communication link established by TRP B and TRP C during the beam failure recovery process. Specifically, Fig.17 It can correspond to the process in which the terminal measures the SINRs of the communication links established with TRP B and TRP C for each candidate beam of TRP A and reports them to each TRP.

[0233] Fig.18 and Fig.19This may correspond to a case where the entity that determines the index of the beam of TRP A that satisfies the SINR threshold is TRP B and TRP C. Specifically, Fig.18 This may correspond to a process in which the terminal additionally sends the index of the beam of TRPA when reporting SINR to TRP B and TRP C. Fig.19 The process may correspond to TRP B and TRP C selecting the index of the beam of TRP A that satisfies their corresponding SINR thresholds, and then sending the selected beam index to TRP A via the terminal.

[0234] Fig. 20 and Fig.21 It may correspond to the case where the entity that determines the index of the beam of TRPA that satisfies the SINR threshold is a terminal. Specifically, Fig. 20 This may correspond to a process in which TRP B and TRP C send their SINR thresholds to the terminal when receiving information about the occurrence of beam failure in the communication link between TRP A and the terminal from the terminal. Fig.21 The process may correspond to the terminal sending the index of the beam of TRP A that meets the SINR threshold to TRP A based on the index of the candidate beam of TRP A and the SINRs of TRP B and TRP C corresponding to the index of the candidate beam of TRP A.

[0235] Fig. 22 It can correspond to TRP A in satisfying Fig.18 and Fig.19 or Fig. 20 and Fig.21 The process of obtaining the threshold TRP A is the process of selecting the beam with the highest SINR among the beams.

[0236] In conclusion, Fig.16 and Fig.17 It may correspond to an operation when a beam failure occurs on the communication link established between TRP A and UE panel A. In this case, in order to select a beam that guarantees a certain level or higher performance of the communication link established between TRB B and UE panel B and the communication link established between TRP C and UE panel C among the candidate beams formed by TRP A for beam failure recovery, TRP A may send an index of a newly formed candidate beam to the terminal.

[0237] If the entity that determines the index of the beam of TRP A that satisfies the SINR threshold of the communication link established between the other TRP and the terminal is another TRP, the terminal can Fig.18 and Fig.19The process reports the index of the candidate beam of TRP A and the SINR of each of TRP B and TRP C for the index of the candidate beam of TRP A to TRP B and TRP C. Then, each of TRP B and TRP C can determine the beam of TRP A that meets its own SINR threshold, and send the determined beam index to TRPA via the terminal.

[0238] On the other hand, if the entity responsible for determination is a terminal, the terminal can Fig. 20 and Fig.21 The process receives the SINR thresholds from TRPB and TRP C, and the terminal can determine the appropriate beam of TRP A and send the index of the determined beam to TRP A.

[0239] at last, Fig. 22 It can correspond to the process that TRP A selects the best beam from the beams of TRP A that meet the SINR threshold of TRP B and the SINR threshold of TRP C. These beams are selected by Fig.18 and Fig.19 or Fig. 20 and Fig.21 The process is notified, thereby taking into account the performance of the communication link between TRP A and the terminal.

[0240] Hereinafter, more detailed operations will be described with reference to each of the drawings.

[0241] Fig.16 is a signal flow diagram for beam failure recovery according to the present invention in an MTRP NCJT environment.

[0242] like Fig.16 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 15 However, with Figures 9 to 15 The situation described in Fig.16 It can be assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0243] Fig.16 The illustrated TRPs 901 to 903 may be TRPs capable of communicating with the terminal 911. In addition, it may be assumed that the terminal has three or more different panels so that it can communicate with different TRPs 901 to 903. For example, it may be assumed that the terminal 911 communicates with TRP A 901 using panel A (not shown), communicates with TRP B 902 using panel B (not shown), and communicates with TRP C 903 using panel C (not shown).

[0244] As described above, when the terminal 911 is communicating with TRP A 901, TRP B 902, and TRP C 903, a beam failure may occur on the communication link with a specific TRP (e.g., TRP A 901).

[0245] In step S1610, the terminal 911 may identify that a beam failure has occurred on a communication link with the TRP A 901. For example, if the number of beam failure instances (BFIs) exceeds the maximum allowed number of communication links established between the terminal 911 and a particular TRP, a beam failure may occur when the terminal 911 declares a beam failure. Therefore, the terminal 911 may be in a situation where a beam failure recovery process needs to be performed. In other words, the occurrence of a beam failure may correspond to a situation where BFI_COUNTER>=beamFailureInstanceMaxCount.

[0246] Here, BFI indicates a condition where a block error rate (BLER) is equal to or greater than a certain threshold, and a count value may be increased by 1 for each BFI. If the count value does not increase within a certain time after the count value is increased by 1, the BFI_COUNTER may be reset to zero (0). When the BFI_COUNTER is reset as described above, it may be interpreted that the BFI no longer occurs.

[0247] If a beam failure occurs as described above, the terminal 911 may transmit beam failure recovery request information to the TRP A 901 through the BeamFailureRecoveryConfig of the RRC signaling including information such as rach-ConfigBFR, rsrp-ThresholdSSB and / or candidateBeamRSList in step S1620.

[0248] In step S1630, the terminal 911 may send the TRP ID of TRP A 901 and information about the beam failure of TRP A to TRP B 902 and TRP C 903, so as to consider the performance of the communication link between other TRPs 902 and TRP 903 and the terminal during the beam failure recovery process between TRP A 901 and the terminal 911. In this case, as described above, the beam failure may have occurred in the communication link between the UE panel A of the terminal 911 and TRP A 901. In this case, the terminal 911 according to the present invention may set the BFD indicator to "1" to indicate the beam failure, and send the beam failure information to TRP B 902 that establishes a communication link with the UE panel B of the terminal 911 and TRP C 903 that establishes a communication link with the UE panel C of the terminal 911.

[0249] In the process of the terminal 911 notifying the TRP B 902 and the TRP C 903 of the beam failure occurring between the TRP A 901 and the UE panel A, an indicator having a different form from the BFD indicator may be sent. For example, the occurrence of the beam failure may be notified through a beam failure detection field (e.g., beam failure detection = enumeration {ON, OFF} or enumeration {TRUE, FALSE}) in the RRC signaling.

[0250] In addition, if TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, the terminal 911 can send the BFD indicator and TRP ID of TRP A to TRP B 902 and TRP C 903 via uplink control information (UCI), measurement report, UE auxiliary information, or RRC signaling newly defined as the TRP ID for notifying beam failure and the TRP where beam failure occurs.

[0251] As another example, if TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, the terminal 911 may send the TRP ID and the BFD indicator of TRP A to TRP B 902 and TRP C 903 through Msg1 or MsgA of a RACH access procedure (hereinafter referred to as "RACH procedure"). As another example, the BFD indicator and the TRP ID of TRP A may be sent through the SN measurement report or SN UE assistance information of SRB3, or SRB3 signaling newly defined according to the present invention to notify the beam failure and the TRP ID of TRP A where the beam failure occurs.

[0252] The information sent from terminal 911 to TRP can be exemplified as shown in Table 8.

[0253] [Table 8]

[0254]

[0255] On the other hand, the above described Fig.16 The exemplary embodiment may be used in combination with at least one of the other exemplary embodiments described below.

[0256] Then, upon receiving information indicating the occurrence of beam failure from TRP A, each of TRP B 902 and TRP C 903 may prepare to measure the SINR of their currently established communication links. During the beam failure recovery process, these links are affected by the candidate beams formed by TRP A for UE Panel A.

[0257] Fig.17 is a signal flow diagram of beam failure recovery according to the present invention in an MTRP NCJT environment.

[0258] like Fig.17 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 16 However, with Figures 9 to 16 The situation described in Fig.17 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0259] Fig.17 It can correspond to a process in which TRP A 901 where a beam failure occurs sends to terminal 911 the index of a candidate beam formed in the process of searching for the best beam through a beam failure recovery process with terminal 911, and terminal 911 observes changes in SINR performance of other TRPs for the index of the candidate beam.

[0260] First, the TRP A901 with beam failure can be based on the above description Fig.16 A beam failure recovery request is received. Therefore, TRP A 901 may perform step S1710 in response to the beam failure recovery request. In this case, TRP A 901 may further perform a process for checking whether it is connected to other TRPs 902 and TRPs 903 that communicate with the terminal 911 via the backhaul. For example, if TRP A 901 is connected to other TRPs 902 and TRPs 903 that communicate with the terminal 911 via the backhaul, it may correspond to the connection through Figures 9 to 15 In the CJT environment described above. Fig.17 The process may correspond to a situation where TRP A 901 is not connected to other TRPs 902 and 903 that communicate with the terminal 911 via a backhaul.

[0261] In step S1710, TRP A 901 may send the index of the candidate beam of TRP A 901 to the terminal 911. In other words, step S1710 may correspond to a step in which the terminal 911 receives the index of the candidate beam from TRP A 901 when TRP A 901 and the UE panel A of the terminal 911 perform a beam failure recovery procedure.

[0262] In step S1720, the terminal 911 may measure the SINR of the communication link between the TRPA B 902 and the UE panel B for the corresponding candidate beam. In this case, the SINR of the communication link between the TRPA B 902 and the UE panel B may be the SINR measured based on the candidate beam of the TRPA 901.

[0263] In addition, in step S1720, the terminal 911 may measure the SINR of the communication link between the TRP C 903 and the UE panel C for the candidate beam. In this case, the SINR of the communication link between the TRP C 903 and the UE panel C may be the SINR measured based on the candidate beam of the TRPA 901.

[0264] because Fig.17 The example corresponds to the operation in the MTRP NCJT environment, a backhaul cannot be formed between TRPs or between base stations connected to the TRPs, and information cannot be directly exchanged between TRPs. Therefore, TRP A 901 can provide terminal 911 with information about the indexes of all its own candidate beams in order to receive the index of a specific beam that satisfies a certain performance or higher performance of the communication link established by TRP B 902 and TRP C 903 with terminal 911 (step S1710).

[0265] In addition, the terminal 911 can measure the SINR of the communication link established by TRP B 902 and TRP C 903 for all candidate beams of TRP A 901 in order to determine the beam that meets the SINR threshold of other TRP 902 and TRP 903.

[0266] The entity that determines the best beam between TRP A 901 and UE panel A of terminal 911 based on the candidate beams of TRP A 901 and the information about the SINRs of TRP B 902 and TRP C 903 of the candidate beams of TRP A 901 may be terminal 911 or other TRP 902 and / or TRP 903.

[0267] If the entity used for determination is terminal 911, terminal 911 may perform Fig.16 and Fig.17 After the process, based on Fig. 20 The SINR threshold obtained by the process is Fig.21 The process selects the best beam.

[0268] On the other hand, Fig.17In the description, only the performance of each beam considering only SINR is described. However, the exemplary embodiment can be extended to a method of considering the performance of each beam by utilizing another criterion for determining a reliable communication link or by considering multiple criteria in combination. For example, the best beam can be selected by considering the delay requirement of terminal 911 or the mobility of terminal 911. When considering the delay requirement of terminal 911, a beam that supports higher performance in terms of user experienced data rate can be selected. As another example, when considering the mobility of terminal 911, a beam that can send data to terminal 911 over a longer period of time can be selected based on the UE mobility or trajectory of terminal 911. As another example, when considering the reliability of the channel, the beam with the smallest change in the measured SINR can also be selected.

[0269] TRP A 901 may send information about the index of its own candidate beam and information indicating the index of the beam (i.e., a beam index report instruction) to the terminal 911 through the UEInformationRequest of the RRC signaling. The beam index report instruction may be indicated as reporting the index of the beam that meets the threshold condition in the neighboring or other TRPs communicating with the terminal 911, such as TRP B 902 and TRP C 903. The conditions in the neighboring or other TRPs communicating with the terminal 911 may exist as various conditions as described above. In the present invention, for ease of description, only SINR will be used for description. Therefore, the conditions in the neighboring or other TRPs communicating with the terminal 911 may be conditions that meet the SINR threshold of other TRPs.

[0270] The terminal 911 receiving the information about the index of the candidate beam and the beam index report instruction may Fig.19 or Fig.21 The information of the index of the beam determined by the process is forwarded to TRP A 901.

[0271] In addition, TRP A 901 may send information indicating the measured SINR for reporting TRP B 902 and TRP C 903 and information about the index of the beam that meets the SINR threshold to the terminal 911 by utilizing an RRC reconfiguration message or RRC signaling newly defined to send such information related to a beam index reporting instruction.

[0272] The information obtained by the terminal 911 in steps S1710 and S1720 may be exemplified as shown in Table 9 below.

[0273] [Table 9]

[0274] Beam index of TRP A SINR of TRP B SINR of TRP C Beam Index = 1 SINR_65 SINR_65 Beam Index = 2 SINR_70 SINR_75 Beam Index = 3 SINR_80 SINR_60 Beam Index = 4 SINR_82 SINR_75 Beam Index = 5 SINR_85 SINR_80

[0275] On the other hand, the above described Fig.17 The exemplary embodiments described above may be Fig.16 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0276] Fig.18 It is a flowchart of a process in which a neighboring TRP of a TRP having a beam failure selects an optimal beam for beam failure recovery according to the present invention in an MTRP NCJT environment.

[0277] like Fig.18 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 17 However, with Fig.16 and Fig.17 Similar to the situation described in Fig.18 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0278] Fig.18 This may correspond to a case where, when beam failure recovery is performed on a communication link established by TRP A 901 and UE panel A of terminal 911, the entities that determine the performance of a communication link established by TRP B 902 and TRP C 903 and UE panel B and UE panel C of terminal 911 are TRP B 902 and TRP C 903. For this purpose, Fig.17 As described in, terminal 911 may need to report to each of TRP 902 and TRP 903 the SINR measured for each of TRP 902 and TRP 903 for the corresponding candidate beams with TRP A901.

[0279] In step S1810a, the terminal 911 may report to the TRP B 902 the SINR between the UE panel B of the terminal 911 and the TRP B 902 for the corresponding candidate beam with the TRP A 901.

[0280] In step S1810b, the terminal 911 may report to the TRP C 903 the SINR between the UE Panel C of the terminal 911 and the TRP C 903 for the corresponding candidate beam with the TRP A 901.

[0281] The reason why the terminal 911 reports the SINR to TRP B 902 and TRP C 903 is that the entities that determine the performance of the communication link are TRP B 902 and TRP C 903. Therefore, considering the NCJT environment, the terminal 911 can send information about the index of the beam to TRP B 902 and TRP C 903. This information has been described as information exchanged via the backhaul between TRPs or between base stations connected to the TRPs in the CJT environment. The information reported by the terminal 911 to TRP B 902 and TRP C 903 described above can be exemplified in Table 10 below.

[0282] [Table 10]

[0283]

[0284] When the Fig.18 Corresponding to the CJT environment Fig.11 When compared with the situation described in , the following explanation can be given.

[0285] exist Fig.11 In the case of NCJT, TRP A 901 can send information about the index of its own candidate beam to TRP B 902 and TRP C 902 via a backhaul between TRPs or between base stations connected to the TRPs. However, in the NCJT environment, TRP A 901 cannot directly send information about the index of its own candidate beam to other TRPs 902 and TRP 903. Therefore, in the present invention, the terminal 911 can be configured as an intermediate repeater, and the terminal 911 can forward such information to TRP B 902 and TRP C 903.

[0286] On the other hand, as illustrated in Table 10, the terminal 911 may forward information about the index of the candidate beam of TRP A 901 to TRP B 902 and TRP C 903 together in the process of reporting the SINRs of TRP B 902 and TRP C 903 measured by the terminal 911. In addition, the terminal 911 may transmit information indicating the index of the beam of TRP A 901 that is reported to satisfy the SINR threshold of the terminal 911 to each of TRP 902 and TRP 903.

[0287] The terminal 911 may send information about the SINRs of TRP B 902 and TRP C 903 for the corresponding candidate beams of TRP A 902. In addition, the terminal 901 may send information indicating the index of the beam that satisfies its SINR threshold to report TRP A 901 to TRP B 902 and TRP C 903. In this case, if TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, the report indication information about the index of the beam of TRP A 901 may be sent through UCI, UE auxiliary information, or new RRC signaling defined according to the present invention to send such information. As another example, if TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, the report instruction information about the index of the beam of TRP A 901 may be sent through Msg1 or MsgA of the RACH process. As another example, the reporting instruction information about the index of the beam of TRP A 901 can be sent through the SN UE assistance information of SRB3, or the SRB3 signaling newly defined according to the present invention to send such information described above.

[0288] In step S1820a, TRP B 902 can select the index of the beam of TRP A 902 that guarantees a certain level or higher performance of the communication link established between TRP B 902 and UE panel B from the index of the candidate beam newly formed by TRP A 901 for UE panel A by utilizing its own SINR received together with the index of the candidate beam of TRP A 901 received from the terminal 911.

[0289] In step S1820b, TRP C 903 can select the index of the beam of TRP A 902 that guarantees a certain level or higher performance of the communication link established between TRP C 903 and UE panel C from the index of the candidate beam newly formed by TRP A901 for UE panel A by utilizing its own SINR received together with the index of the candidate beam of TRP A901 received from the terminal 911.

[0290] On the other hand, Fig.18In the description, only the performance of each beam considering only SINR is described. However, the exemplary embodiment can be extended to a method of considering the performance of each beam by utilizing another criterion for determining a reliable communication link or by considering multiple criteria in combination. For example, the best beam can be selected by considering the delay requirement of terminal 911 or the mobility of terminal 911. When considering the delay requirement of terminal 911, a beam that supports higher performance in terms of user experienced data rate can be selected. As another example, when considering the mobility of terminal 911, a beam that can send data to terminal 911 over a longer period of time can be selected based on the UE mobility or trajectory of terminal 911. As another example, when considering the reliability of the channel, the beam with the smallest change in the measured SINR can also be selected.

[0291] On the other hand, the above described Fig.18 The exemplary embodiments described above may be Fig.16 and Fig.17 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0292] Fig.19 is a signal flow diagram of a process in which a TRP in which a beam failure occurs selects an optimal beam for beam failure recovery based on information received from neighboring TRPs via a terminal according to the present invention in an MTRP NCJT environment.

[0293] like Fig.19 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 19 However, with Figures 16 to 18 Similar to the situation described in Fig.19 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0294] Fig.19 The signal flow may correspond to the signal flow in the case where, when beam failure recovery is performed on the communication link formed between TRP A 901 of terminal 911 and UE panel A, the entities that determine the performance of the communication link between TRP B 902 and UE panel B of terminal 911 and the performance of the communication link between TRP C 903 and UE panel C of terminal 911 are TRP B 902 and TRP C 903, respectively.

[0295] Fig.19 Each of TRP B 902 and TRP C 903 can be based on the above Fig.18The process of determining the index of the beam of TRP A 901 that satisfies its threshold condition from the information received from the terminal 911. Each of TRP B 902 and TRP C 903 may generate a message including the index of the beam that satisfies the threshold condition based on such determination.

[0296] In step S1910a, TRP B 902 may send a message generated based on the above description to terminal 911, that is, a message including the index of the beam of TRP A 901 that meets the threshold condition.

[0297] In step S1910b, TRP C 903 may send a message generated based on the above description to Terminal 911, that is, a message including the index of the beam of TRP A 901 that meets the threshold condition.

[0298] This will be done by assuming Fig.12 The situation of Table 4 described in is further described in detail.

[0299] In the case of Table 4, among the indices of candidate beams of TRP A, the indices of beams of TRP A 901 that satisfy the threshold condition of TRP B 902 may be beam index 3, beam index 4, and beam index 5. Therefore, the message sent to the terminal in step S1910a may include information about beam index 3, beam index 4, and beam index 5.

[0300] In the case of Table 4, among the indices of candidate beams of TRP A, the indices of beams of TRP A 901 that satisfy the threshold condition of TRP C 903 may be beam index 2, beam index 4, and beam index 5. Therefore, the message sent to the terminal in step S1910b may include information about beam index 2, beam index 4, and beam index 5.

[0301] In steps S1910a and S1910b, the terminal 911 may receive the index of the beam of TRP A 901 from each of TRP B 902 and TRP C 903. Therefore, the terminal 911 may generate a message including the index of the beam of TRP A 901 received from each of TRP B 902 and TRP C 903. In step S1920, the terminal 911 may transmit the generated message including the index of the beam of TRP A 901 in each of TRP 902 and TRP 903 that satisfies the SINR threshold to TRP A 901.

[0302] Thereafter, TRP A 901 may select a beam that can guarantee a certain level or higher of communication performance of the communication link established between TRP B 902 and UE panel B of terminal 911 and the communication link established between TRP C 903 and UE panel C of terminal 911, among candidate beams formed between itself and UE panel A of terminal 911, based on the index of the beam that satisfies the SINR threshold in TRP B 902 and TRP C 903 forwarded by terminal 911. This means that even if TRP A 901 selects any one of beam index 4 or beam index 5 of TRP A 901 during the beam failure recovery process, beam failure may not occur on the communication link between TRP B 902 and UE panel B of terminal 911 and the communication link between TRP C 903 and UE panel C of terminal 911. In addition, even if TRP A901 selects either beam index 4 or beam index 5 of TRP A901 during the beam failure recovery process, the performance degradation of the communication link between TRP B 902 and UE panel B of terminal 911 and the communication link between TRP C 903 and UE panel C of terminal 911 can be minimized.

[0303] Meanwhile, the messages of step S1910a and step S1910b may be configured differently depending on the base stations to which TRP A 901, TRP B 902, and TRP C 903 are connected. For example, if TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, TRP B 902 and TRP C 903 may send the index of the beam of TRP A 901 that meets its SINR threshold to the terminal 911 through RRC signaling newly defined as sending such information described in the present invention.

[0304] If TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, TRP B 902 and TRP C 903 may send information to the terminal 911 via Msg2 or MsgB of the RACH process, or via SRB3 signaling newly defined to send such information described in the present invention.

[0305] Based on the above description Fig.19 The information sent in can be exemplified as shown in Table 11 below.

[0306] [Table 11]

[0307]

[0308]

[0309] As illustrated in Table 11, as in Scheme 1, Terminal 911 may send both TRPID and the index of the beam transmitted by the corresponding TRP in the message sent to TRP A 901. In Scheme 1, the amount of information that Terminal 911 needs to send increases, but Terminal 911 may send the information without processing it.

[0310] In addition, in scheme 2, the terminal 911 may identify the index of the beam notified by TRP B 902 and the index of the beam notified by TRP C 903, and select a common beam index. Then, the terminal 911 may send only the common beam index to TRP A 901. When scheme 2 is utilized, the terminal 911 may need to process information sent by TRP B 902 and TRP C 903. Therefore, the processing load on the terminal 911 may increase. However, scheme 2 has the advantage of reducing the amount of information sent by the terminal 911 to TRP A 901.

[0311] On the other hand, the message reported by the terminal 911 to TRP A 901 may vary based on the type of message received from TRP A 901. For example, when receiving information indicating the index of the beam that reports the SINR threshold of other TRPs through UEInformationRequest of RRC signaling in Table 17 above from TRP A 901, the terminal 911 may send the information obtained from TRP B 902 and TRP C 903 to TRP A 901 through UEInformationResponse.

[0312] As another example, in order to report to TRP A901 the index of the beam that meets the SINR threshold of other TRPs, Terminal 911 can utilize UCI, measurement report, UE assistance information, or RRC signaling newly defined according to the present invention to send such information.

[0313] As another example, the information reporting process of terminal 911 may use Msg1 or MsgA of RACH process. As another example, terminal 911 may send information through SRB3 using SN measurement report or SN UE assistance information, or SRB3 signaling newly defined according to the present invention to send such information.

[0314] On the other hand, the above described Fig.19 The exemplary embodiments described above may be Figures 16 to 18 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0315] Fig. 201 is a signal flow diagram of a process in which a terminal having a beam failure receives information for beam failure recovery from a neighboring TRP according to the present invention in an MTRP NCJT environment.

[0316] like Fig. 20 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 19 However, with Figures 16 to 19 Similar to the situation described in Fig. 20 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0317] Fig. 20 It can correspond to a situation where terminal 911 is an entity that determines a beam from among the candidate beams formed by TRP A901 that can guarantee the performance of the communication link previously established by other TRPs and terminal 911 when a beam failure occurs in the communication link between TRP A901 and UE panel A and beam failure recovery is performed.

[0318] Terminal 911 may have already been Fig.17 The candidate beam of TRP A 901 in the communication link established with TRP B 902 is measured. In addition, the terminal 911 may have measured the SINR of the communication link established with TRP C 903 for the candidate beam of TRP A 901. However, the terminal 911 cannot identify whether the measured SINR meets the SINR threshold required by TRP B 902 and TRP C 903.

[0319] Fig. 20 The operation may correspond to a process for obtaining information that can verify whether the SINR measured for the candidate beam of TRP A 901 from the signals sent from the neighboring TRP 902 and TRP 903 communicating with the terminal 911 satisfies the corresponding SINR thresholds of the neighboring TRP 902 and TRP 903.

[0320] In step S2010a, TRP C 903 may send the SINR threshold of TRP C 903 to the terminal 911. In addition, in step S2010b, TRP B 902 may send the SINR threshold of TRP B 902 to the terminal 911. In this case, the SINR threshold of TRP C 903 and the SINR threshold of TRP B 902 may be the same value or different values. The SINR threshold may be determined by considering various factors such as the performance of the devices constituting the TRP or the coverage of the TRP, or may be determined based on the surrounding environment, etc. As another example, the SINR threshold of the TRP may be determined based on actual measurement.

[0321] The SINR threshold sent by TRP B 902 and TRP C 903 to the terminal 911 may be exemplified as shown in Table 12 below.

[0322] [Table 12]

[0323] SINR Threshold TRP B → UE Panel B SINR_75 TRP C → UE Panel C SINR_70

[0324] in addition, Fig. 20 The process can be executed as before Fig.17 As another example, Fig. 20 The process may be a process in which all TRPs send their SINR thresholds to the terminal 911 when initiating MTRP operation. If the process causes all TRPs to send their SINR thresholds to the terminal 911 when initiating MTRP operation, then TRP A901 may already be in Fig. 20 The SINR threshold is sent to the terminal 911 in advance in a step not shown in FIG.

[0325] For example, when the terminal 911 initially establishes a communication link with TRP A 901, the terminal 911 may receive information about the SINR threshold from TRP A 901. Thereafter, when TRP B 902 and TRP C 903 send additional data to the terminal 911, each of TRP B 902 and TRP C 903 may send information about its own SINR threshold to the terminal 911. Fig. 20 An example of this situation can be shown.

[0326] As another example, if the entity determining the performance of the communication link is terminal 911, and a beam failure occurs between terminal 911 and TRP A 901, terminal 911 may send the TRP ID and BFD indicator of TRP A 901 to neighboring TRPs 902 and 903, as described above. Fig.16Therefore, if the entity determining the performance of the communication link is the terminal 911, and the information about the SINR threshold is not received from each of the TRPs 901 to 903 in the initial process, the terminal 911 may request the SINR threshold of each TRP in step S1630. Therefore, the SINR threshold may be received as a response. Fig. 20 Response to step S1630 in .

[0327] On the other hand, if you execute Fig. 20 The process corresponds to Fig.16 In response to step S1630, Fig.16 The SINR threshold request information may be sent to neighboring TRPs 902 and 903 together with the TRP ID and BFD indicator of TRP A where beam failure occurs.

[0328] If TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, the terminal 911 may send the above information to TRP B 902 and TRP C 903 using UCI, UE auxiliary information, or RRC signaling newly defined according to the present invention.

[0329] On the other hand, if TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, the terminal 911 may transmit the above-described information to TRP B 902 and TRP C 903 using Msg1 or MsgA of the RACH process. As another example, if TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, the terminal 911 may transmit the above-described information to TRP B 902 and TRP C 903 through SN UE assistance information newly defined as SRB3 or SRB3 signaling for transmitting such information according to the present invention.

[0330] Send to Fig. 20 The SINR threshold of terminal 911 in can also be sent differently according to the connection relationship of TRP.

[0331] For example, if TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, TRP B 902 and TRP C 903 may send the SINR threshold to the terminal 911 through the DCI of the previously established communication link. As another example, if TRP B 902 and TRP C 903 are connected to the same base station as the base station to which TRP A 901 is connected, TRP B 902 and TRP C 903 may send the SINR threshold to the terminal 911 through the MeasConfig IE of the RRC reconfiguration message or the RRC signaling newly defined as sending the SINR threshold according to the present invention.

[0332] On the other hand, if TRP B 902 and TRP C 903 are connected to a base station different from the base station to which TRP A 901 is connected, TRP B 902 and TRP C 903 may send the SINR threshold to the terminal 911 through DCI, Msg2, or MsgB.

[0333] Terminal 911 can Fig. 20 The SINR threshold for each TRP received in Fig.17 The SINR of each of the candidate beams of TRPA measured in TRP B 902 and TRP C 903 is compared to determine which beam of TRP A to use.

[0334] On the other hand, the above described Fig. 20 The exemplary embodiments described above may be Figures 16 to 19 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0335] Fig.21 It is a signal flow diagram of a process of determining beam failure recovery at a terminal having beam failure according to the present invention in an MTRP NCJT environment.

[0336] like Fig.21 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 19 However, with Figures 16 to 20 Similar to the situation described in Fig.21 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0337] Fig.21Corresponding to a signal flow diagram when beam failure recovery is performed on a communication link between TRP A 901 and UE panel A of terminal 911. In this case, terminal 911 may be an entity that determines the performance of a communication link between TRP B 902 and UE panel B of terminal 911. In addition, terminal 911 may be an entity that determines the performance of a communication link between TRP C 903 and UE panel C of terminal 911.

[0338] Through the above Fig.17 The terminal 911 may have the SINR measured between TRP B 902 and UE panel B of the terminal 911 for the corresponding candidate beam of TRP A 901, and may have the SINR measured between TRP C 903 and UE panel C of the terminal 911 for the corresponding candidate beam of TRP A 901. In addition, through the above-described Fig. 20 During the process, the terminal 911 may have received the SINR threshold of TRP B 902 and the SINR threshold of TRP C 903.

[0339] In step S2110, the terminal 911 can Fig.17 The index of the beam of TRP A 901 is selected based on the SINR between the neighboring TRP 902 and TRP 903 and the terminal 911 measured by the corresponding candidate beam of TRP A 901 in FIG. 1 and the SINR thresholds received from TRP 902 and TRP 903. In this case, it can be assumed that the terminal 911 has measured the SINRs of TRP B 902 and TRP C 903, as shown in Table 4 described above. In addition, it can be assumed that the SINR threshold condition of TRP B 902 is that the SINR exceeds 75, and the SINR threshold condition of TRP C 903 is that the SINR threshold exceeds 70.

[0340] In this case, the terminal 911 may determine beam index 3, beam index 4, and beam index 5 as the index of the beam that satisfies the SINR threshold condition of TRP B 902 among the candidate beams between TRP A 901 of the terminal 911 and UE panel A. In addition, the terminal 911 may determine beam index 2, beam index 4, and beam index 5 as the index of the beam that satisfies the SINR threshold condition of TRP C 903 among the candidate beams between TRP A 901 of the terminal 911 and UE panel A. The index of the beam that satisfies the threshold condition may be the index of the beam that can guarantee the communication link between the terminal 911 and the specific TRP.

[0341] For example, among the candidate beams between terminal 911 and TRP A 901, the beams identified by beam index 3, beam index 4, and beam index 5 may be beams that will not cause beam failure of the communication link established between TRP B 902 and terminal 911 or may minimize the deterioration of the communication quality in the communication link.

[0342] Similarly, among the candidate beams between terminal 911 and TRP A 901, beams identified by beam index 2, beam index 4, and beam index 5 may be beams that will not cause beam failure of the communication link established between TRP C 903 and terminal 911 or may minimize the deterioration of the communication quality in the communication link.

[0343] Therefore, terminal 911 can confirm that the indices of common beams that satisfy both thresholds of TRP B 902 and TRP C 903 among the candidate beams between terminal 911 and TRP A 901 are beam index 4 and beam index 5.

[0344] In step S2120, the terminal 911 may send information about the index of the beam of the TRPA that meets the SINR threshold to the TRPA 901. The terminal 911 may send information about the index of the beam of the TRPA that meets the SINR threshold using scheme 1 or scheme 2. This may be exemplified as shown in the following Table 13.

[0345] [Table 13]

[0346]

[0347] As described in Table 11 above, when using Scheme 1, since Terminal 911 sends information without any special processing, the load of Terminal 911 can be reduced. On the other hand, when using Scheme 2, the amount of information sent by Terminal 911 to TRP A 901 can be reduced.

[0348] Table 13 illustrates a case where all beam indexes that can be selected by the transmitting terminal 11 are transmitted. For example, in scheme 1, beam index 3, beam index 4, and beam index 5 are transmitted as beam indexes selected by TRP B 902, and beam index 2, beam index 4, and beam index 5 are transmitted as beam indexes selected by TRP C 903. On the other hand, in scheme 2, beam index 4 and beam index 5, which are common beam indexes of the index of the beam selected by TRP B 902 and the index of the beam selected by TRP C 903, may be transmitted.

[0349] However, as another example, the terminal 911 may select a specific beam based on the index of the preferred beam. In this case, scheme 2 may be used to send only one preferred beam index, beam index 4 or beam index 5. As another example, the index of the beam may be sent as in scheme 2, but the beam index preferred by the terminal 911 may be sent together. When the terminal 911 sends the preferred beam index to TRP A901, the terminal 911 may be configured to send the preferred beam index together even in the case of scheme 1.

[0350] On the other hand, in response to Fig.17 Step S2120 is performed based on the index of the beam of TRPA 901 sent to the terminal 911 by step S1710. Therefore, the message sent in step S2120 can be determined based on the type of the message sent in the previous step S1710.

[0351] For example, if information indicating the index of a beam for reporting an SINR threshold that meets another TRP is received through the UEInformationRequest of the RRC signaling of step S1710, the terminal 911 can send corresponding information to the base station through the UEInformationResponse of step S2120 in response to the instruction information.

[0352] As another example, the terminal 911 may send information about the index of a beam that meets the SINR threshold of another TRP to TRP A 901 using UCI, UE assistance information, or RRC signaling newly defined to send such information according to the present invention.

[0353] As another example, the terminal 911 may send information according to scheme 1 or information according to scheme 2 to the TRPA 901 by using the Msg1 or MsgA of the RACH process.

[0354] As another example, the terminal 911 can use the SN UE assistance information through SRB3, or use the SRB3 signaling newly defined to send such information according to the present invention, to send information according to scheme 1 or information according to scheme 2 to TRP A 901.

[0355] On the other hand, the above described Fig.21 The exemplary embodiments described above may be Figures 16 to 20 The exemplary embodiments and / or at least one of the other exemplary embodiments described below may be used in combination.

[0356] Fig. 22 is a flow chart of a process for determining a beam to be used for beam failure recovery when a beam failure occurs according to the present invention in an MTRP NCJT environment.

[0357] like Fig. 22 As shown, TRP A 901, TRP B 902 and TRP C 903 are Figures 9 to 19 However, with Figures 16 to 21 Similar to the situation described in Fig. 22 It is assumed that TRP A 901, TRP B 902, and TRP C 903 cannot send and receive data via a backhaul connected directly or through a base station.

[0358] Fig. 22 The process of TRP A 901 selecting the best beam by considering the performance of the communication link between the terminal 911 and other TRPs and the performance of the communication link between itself and the terminal when selecting the beam to be used for communication, in which a beam failure occurs.

[0359] Therefore, TRP A901 can be Fig.21 The processing scheme 1 or scheme 2 receives the index of the beam that can guarantee the performance of the communication link between TRP B 902 and UE panel B of terminal 911 among the candidate beams formed by TRP A 901 for UE panel A of terminal 911. In addition, TRP A 901 can Fig.21 Processing scheme 1 or scheme 2 receives the index of the beam that can guarantee the performance of the communication link between TRP C 903 and UE panel C of terminal 911 among the candidate beams formed by TRPA 901 for UE panel A of terminal 911.

[0360] TRP A 901 may select the index of the beam to be used for communication with the terminal 911 based on the above information. In this case, TRP A 901 may select the index of the beam in consideration of the performance of the communication link between TRP A 901 and the terminal 911. In addition, TRP A 901 may select the index of the beam to be used for communication with the terminal 911 in consideration of the performance of the communication link with other terminals.

[0361] If the terminal 911 is Fig.21 In the process of sending information about the index of the beam that meets the SINR threshold and information about the TRP ID corresponding thereto using scheme 1, TRP A 901 can know which beam indexes meet the thresholds that respectively satisfy TRPB 902 and TRP C 903. Therefore, TRP A 901 can select the index of the beam of TRPA 901 that will eventually be used for UE panel A of terminal 911 based on the information described above.

[0362] If the terminal 911 is Fig.21In the process, scheme 2 is used to send only the index of the common beam that meets the SINR thresholds of both TRP B 902 and TRPC 903 to TRP A 901. Then TRP A 901 can select the index of the beam of TRP A901 that will eventually be used for UE panel A of terminal 911 based on the corresponding information.

[0363] Accordingly, in Fig.21 In the case of a fault, during the process of selecting a final beam index to be used when performing a beam failure recovery process with UE panel A of terminal 911, TRP A 901 may receive the index of the beam of TRP A 901 that satisfies a certain level or higher of communication performance from TRP B 902 and TRP C 903. Then, TRP A 901 may select the best beam among the indexes of the received beams of TRP A 901.

[0364] The combination of beams that can be selected by TRP A 901 based on the SINR values ​​of Scheme 1 and Scheme 2 can be exemplified as shown in Table 14 below.

[0365] [Table 14]

[0366]

[0367] On the other hand, the above described Fig. 22 The exemplary embodiments described above may be Figures 16 to 21 At least one of the exemplary embodiments of the present invention is used in combination.

[0368] Fig.23 is a flow chart of a process of performing beam failure recovery in an MTRP NCJT environment according to an exemplary embodiment of the present invention.

[0369] In the description Fig.23 When Figures 16 to 22 901, TRP B 902, TRP C 903, and terminal 911 described in the MTRP NCJT are described. Since they operate in the MTRP NCJT environment, it is assumed that data cannot be sent and received via a directly connected backhaul or a backhaul connected through a base station.

[0370] like Fig.23As shown, in step 2310, the terminal 911 may send information about the beam failure to TRP B 902 and TRP C 903, and measure the SINR of the signals from TRP B 902 and TRP C 903. In this case, the beam failure may be a beam failure between TRP A 901 and the terminal 911. Therefore, the terminal 911 may send the TRP ID of TRP A 901 to TRP B 902 and TRP C 903 to notify the beam failure of TRP A 901. In addition, when the terminal 911 measures the SINR of the signals received from TRP B 902 and TRP C 903, the terminal may measure the SINR of the index of the candidate beam of TRP A 901. Although in Fig.23 Not shown in the figure, the terminal 911 may have received information about the index of the candidate beam of TRP A 901 from TRP A 901. In addition, the terminal 911 may report the SINR measured from TRP B 902 to TRP B 902. In this case, the SINR reported by the terminal 911 to TRP B 902 may be the SINR measured on the communication link between TRP B 902 and the terminal 911 for the corresponding candidate beam between the terminal 911 and TRP A 901, and the SINR reported by the terminal 911 to TRP C 903 may be the SINR measured on the communication link between TRP C 903 and the terminal 911 for the corresponding candidate beam between the terminal 911 and TRP A 901.

[0371] like Fig.23 As shown, one of the two types may be determined according to an entity that determines the index of the beam used for beam failure recovery after step 2310 .

[0372] If the TRP determines the index of the beam to be used for beam failure recovery, steps 2320 and 2330 may be performed. On the other hand, if the terminal determines the index of the beam index to be used for beam failure recovery, steps 2340, 2350, and 2360 may be performed.

[0373] First, the case where TRP determines the index of the beam to be used for beam failure recovery will be described.

[0374] In step 2320, the terminal 911 may transmit information about the index of the beam satisfying the SINR threshold of the corresponding TRP 902 and TRP 903 to TRP A 901 based on the SINR threshold received from TRP B 902 and TRP C 903 in step 2310, using one of schemes 1 or 2 as shown in Table 11 described above. The operation of step 2320 may correspond to an operation in which each of TRP B 902 and TRP C 903 transmits information about the index of the beam satisfying the SINR threshold to TRP A 901 through the terminal 911.

[0375] In step 2330, TRP A901 may select a beam having the highest SINR as a beam to be used for beam failure recovery between terminal 911 and TRP A901 based on the index of the beam satisfying the SINR threshold received from terminal 911.

[0376] Hereinafter, a case in which the terminal determines an index of a beam to be used for beam failure recovery will be described.

[0377] In step 2340, the terminal 911 may receive an SINR threshold value from each of the TRP B 902 and the TRP C 903. In other words, the terminal 911 may request an SINR threshold value from the TRP B 902 and receive the SINR threshold value of the TRP B 902 from the TRP B 902. In addition, the terminal 911 may request an SINR threshold value from the TRP C 903 and receive the SINR threshold value of the TRP C 903 from the TRP C 903.

[0378] In step 2350, the terminal 911 may determine the index of the beam based on the SINR threshold received from each of TRP B 902 and TRP C 903. In other words, the terminal 911 may determine the index or beam having an SINR exceeding (or equal to or higher than) the SINR threshold from the SINR measured on the communication link between TRP B 902 and the terminal 911 for the corresponding candidate beam between the terminal 911 and TRP A 901 described in step 2310 above. The index of the beam may be determined for TRP C 903 in the same manner. Accordingly, the terminal 911 may utilize Fig.21 Scheme 1 or Scheme 2 described in sends information about the index of the beam to TRP A901.

[0379] In step 2350, TRP A 901 may receive information from terminal 911 about the index of the beam of the communication link of neighboring TRP 902 and TRP 903 that can maintain communication with terminal 911 using scheme 1 or scheme 2.

[0380] In step 2360 , TRPA 901 may select the index of the beam having the highest SINR based on the index of the beam received from the terminal 911 .

[0381] Described above Fig.23 It can correspond to the above description based on Figures 16 to 22 An exemplary embodiment of .

[0382] Fig.24 is a signal flow diagram of a process of performing beam recovery for a TRP with beam failure according to the present invention in an MTRP NCJT environment.

[0383] Fig.24 It can be based on the above description Figures 16 to 22 Flow graph for a specific combination of .

[0384] Step S2410, step S2412 and step S2414 may correspond to Fig.16 Step S1610, step S1620 and step S1630 described in the above. Step S2416 and step S2418 may correspond to Fig.17 Step S1710 and step S1720 described in . In addition, step S2420 may correspond to Fig.18 Steps S1810a and S1810b described in , and steps S2422a and S2422b may correspond to Fig.18 Step S1820a and step S1820b described in.

[0385] Step S2424a and step S2424b may correspond to Fig.19 Steps S1910a and S1910b described in , and step S2426 may correspond to Fig.19 Step S1920 described in . Step S2428 may correspond to Fig. 22 Step S2210 described in .

[0386] therefore, Fig.24 An exemplary embodiment may be to sequentially execute the above described Figures 16 to 19 process and then execute Fig. 22 In addition, Fig.24 An exemplary embodiment may be an exemplary embodiment in which the TRP operates as an entity that determines the index of a beam to be used for beam failure recovery.

[0387] Fig.25 It is a signal flow diagram of a process of performing beam failure recovery on a terminal having a beam failure according to the present invention in an MTRP NCJT environment.

[0388] Fig.25 It can be based on the above description Figures 16 to 22 Flowchart of a specific combination of .

[0389] Step S2510, step S2512 and step S2514 may correspond to Fig.16 In addition, step S2520 may be a combination of the steps S1610, S1620 and S1630 described above. Fig.17 and Fig. 20 process.

[0390] For example, step S2520c may correspond to the above-described Fig.17 Therefore, step S1710 can be omitted. Fig.17 Step S1720. Step S2520a and step S2520b may correspond to Fig. 20 Step S1910a and step S1910b described in.

[0391] In addition, step S2530 and step S2532 may correspond to the above-described Fig.21 Step S2534 may correspond to Fig. 22 Step S2210 described in .

[0392] therefore, Fig.25 An exemplary embodiment may be described above. Fig.16 After the process is executed Fig.17 and Fig. 20 process, and then execute Fig.21 and Fig. 22 In addition, Fig.25 An exemplary embodiment may be an exemplary embodiment in which a terminal operates as an entity that determines an index of a beam to be used for beam failure recovery.

[0393] Described above Fig.24 and Fig.25 It can be a combination of the above Figures 16 to 22 Therefore, in addition to Fig.24 and Fig.25 In addition to the methods shown, you can use Figures 16 to 22 In addition, Figures 16 to 22 At least one of the processes may be used in combination with other types of operations not illustrated in the present invention.

[0394] The operation of the method according to the exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include a recording device of all types having data that can be read by a computer system. In addition, the computer-readable recording medium can store and execute programs or codes, which can be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0395] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM or flash memory. Program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0396] Although some aspects of the present invention have been described in the context of a device, these aspects may indicate the corresponding description according to the method, and a block or device may correspond to the step of the method or the feature of the step. Similarly, the aspects described in the context of the method may be represented as the feature of a corresponding block or project or a corresponding device. Some or all steps of the method may be performed by (or using) a hardware device such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important steps of the method may be performed by such a device.

[0397] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the field programmable gate array can be operated with a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a specific hardware device.

[0398] The description of the present invention is merely exemplary in nature, and therefore variant forms that do not deviate from the essence of the present invention are intended to be within the scope of the present invention. Such variant forms should not be considered as departing from the spirit and scope of the present invention. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A terminal method, comprising: In response to a beam failure occurring at a first transmission and reception point (TRP) in communication with the terminal, sending a beam failure recovery request to the first TRP; Sending a first message to a second TRP in communication with the terminal, the first message including an identifier (ID) of the first TRP and a beam failure detection (BFD) indicator; receiving a second message from the first TRP, the second message comprising respective beam indices corresponding to candidate beams to be used between the first TRP and the terminal; For the corresponding beam index, measuring a signal to interference plus noise ratio (SINR) of the first link communicating with the second TRP; In response to the first message, receiving a third message from the second TRP, the third message including an SINR threshold for the first link; as well as In response to the second message, a first report message is sent to the first TRP, wherein the first report message includes information related to the index of the beam that meets the SINR threshold of the first link.

2. The method according to claim 1, further comprising: In response to the presence of a third TRP communicating with the terminal, sending a fourth message to the third TRP, the fourth message including an ID of the first TRP and a BFD indicator; For the corresponding beam index, measuring the SINR of the second link communicating with the third TRP; and In response to the fourth message, receiving a fifth message from the third TRP, the fifth message including an SINR threshold for the second link, The first report message further includes information related to the index of the beam that meets the SINR threshold of the second link.

3. The method according to claim 2, wherein: The first report message includes: the ID of the second TRP, the index of the beam that meets the SINR threshold of the first link, the ID of the third TRP, and the index of the beam that meets the SINR threshold of the second link.

4. The method according to claim 2, wherein: The first report message includes a common index of an index of a beam satisfying an SINR threshold of a first link and an index of an index of a beam satisfying an SINR threshold of a second link.

5. The method according to claim 1, wherein: Each of the second message and the first report message is transmitted and received using a radio resource control (RRC) signaling message.

6. The method according to claim 1, wherein: When the first TRP and the second TRP are connected to the same base station, the first message is sent using one of uplink control information (UCI), measurement report, or user equipment (UE) assistance information.

7. The method according to claim 1, wherein: When the first TRP and the second TRP are connected to different base stations, the first message is sent using a message based on a random access channel (RACH) access procedure.

8. A method of a first transmission and reception point (TRP), comprising: Upon receiving a beam failure recovery request from a terminal in communication with a first TRP, checking whether the first TRP is connected to a second TRP in communication with the terminal via a backhaul; In response to the first TRP not being connected to the second TRP via a backhaul, sending a first message to the terminal, the first message including a beam index of a candidate beam between the first TRP and the terminal; In response to the first message, receiving a first report message from the terminal, the first report message including information related to an index of the beam; as well as The index of the beam to be used for communication with the terminal is determined based on the information related to the index of the beam.

9. The method according to claim 8, wherein: The first report message includes an identifier (ID) of the second TRP and an index of at least one beam that meets a signal to interference plus noise ratio (SINR) threshold of a first link between the second TRP and the terminal.

10. The method according to claim 9, wherein: When there is a third TRP communicating with the terminal, the first report message further includes the ID of the third TRP ID and the index of at least one beam that meets the SINR threshold of the second link between the third TRP and the terminal.

11. The method according to claim 8, wherein: When the first report message includes two or more beam indices, an index of a beam to be used for communication with the terminal is determined based on SINRs reported together with the corresponding two or more beam indices.

12. The method according to claim 8, wherein: Each of the first message and the first report message is transmitted and received using a radio resource control (RRC) signaling message.

13. A method of a terminal, comprising: In response to a beam failure occurring at a first transmission and reception point (TRP) in communication with the terminal, sending a beam failure recovery request to the first TRP; Sending a first message to a second TRP in communication with the terminal, the first message including an identifier (ID) of the first TRP and a beam failure detection (BFD) indicator; receiving a second message from the first TRP, the second message comprising respective beam indices corresponding to candidate beams to be used between the first TRP and the terminal; For the corresponding beam index, measuring a signal to interference plus noise ratio (SINR) of the first link communicating with the second TRP; Sending a third message to a second TRP, the third message comprising a measured SINR for a corresponding beam index; In response to the first message, receiving a fourth message from the second TRP, the fourth message including an index of at least one beam; as well as A first report message is sent to the first TRP, wherein the first report message includes information related to an index of a beam based on a fourth message received from the second TRP.

14. The method according to claim 13, further comprising: In response to the presence of a third TRP communicating with the terminal, sending a fifth message to the third TRP, the fifth message including an ID of the first TRP and a BFD indicator; For the corresponding beam index, measuring the SINR of the second link communicating with the third TRP; sending a sixth message to the third TRP, the sixth message comprising a measured SINR for a corresponding beam index; and receiving, in response to the fifth message, a seventh message from the third TRP, the seventh message including an index of at least one beam, The first report message further includes information related to the index of the beam based on the seventh message.

15. The method according to claim 14, wherein: The first report message includes: the ID of the second TRP, the index of the beam that meets the SINR threshold of the first link, the ID of the third TRP, and the index of the beam that meets the SINR threshold of the second link.

16. The method according to claim 14, wherein: The first report message includes only a common index of an index of at least one beam included in the fourth message and an index of at least one beam included in the seventh message.

17. The method according to claim 13, wherein: Each of the second message and the first report message is transmitted and received using a radio resource control (RRC) signaling message.

18. The method according to claim 13, wherein: When the first TRP and the second TRP are connected to the same base station, the first message is sent using one of uplink control information (UCI), measurement report, or user equipment (UE) assistance information.

19. The method according to claim 13, wherein: When the first TRP and the second TRP are connected to different base stations, the first message is sent using a message based on a random access channel (RACH) access procedure.

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